Glucosyltransferase enzymes for production of glucan polymers

ABSTRACT

Compositions are disclosed herein comprising poly alpha-1,3-1,6-glucan with a weight average degree of polymerization (DP w ) of at least 1000. This glucan polymer comprises at least 30% alpha-1,3 linkages and at least 30% alpha-1,6 linkages. Further disclosed are glucosyltransferase enzymes that synthesize poly alpha-1,3-1,6-glucan. Ether derivatives of poly alpha-1,3-1,6-glucan and methods of using such derivatives as viscosity modifiers are also disclosed.

This application claims the benefit of U.S. Provisional Application No.61/939,811 (filed Feb. 14, 2014), which is incorporated herein byreference in its entirety.

FIELD OF INVENTION

This invention is in the field of polysaccharides and polysaccharidederivatives. Specifically, this invention pertains to certain polyalpha-1,3-1,6-glucans, glucosyltransferase enzymes that synthesize theseglucans, ethers of these glucans, and use of such ethers as viscositymodifiers.

BACKGROUND

Driven by a desire to find new structural polysaccharides usingenzymatic syntheses or genetic engineering of microorganisms,researchers have discovered polysaccharides that are biodegradable andcan be made economically from renewably sourced feedstocks. One suchpolysaccharide is poly alpha-1,3-glucan, a glucan polymer characterizedby having alpha-1,3-glycosidic linkages.

Poly alpha-1,3-glucan has been isolated by contacting an aqueoussolution of sucrose with a glucosyltransferase (gtf) enzyme isolatedfrom Streptococcus salivarius (Simpson et al., Microbiology141:1451-1460, 1995). U.S. Pat. No. 7,000,000 disclosed the preparationof a polysaccharide fiber using an S. salivarius gtfJ enzyme. At least50% of the hexose units within the polymer of this fiber were linked viaalpha-1,3-glycosidic linkages. The disclosed polymer formed a liquidcrystalline solution when it was dissolved above a criticalconcentration in a solvent or in a mixture comprising a solvent. Fromthis solution continuous, strong, cotton-like fibers, highly suitablefor use in textiles, were spun and used.

Development of new glucan polysaccharides and derivatives thereof isdesirable given their potential utility in various applications. It isalso desirable to identify glucosyltransferase enzymes that cansynthesize new glucan polysaccharides, especially those with mixedglycosidic linkages and high molecular weight.

SUMMARY OF INVENTION

In one embodiment, the invention concerns a reaction solution comprisingwater, sucrose and a glucosyltransferase enzyme that synthesizes polyalpha-1,3-1,6-glucan. The glucosyltransferase enzyme comprises an aminoacid sequence that is at least 90% identical to SEQ ID NO:2, SEQ IDNO:4, SEQ ID NO:6, SEQ ID NO:8, or SEQ ID NO:10.

In a second embodiment, (i) at least 30% of the glycosidic linkages ofthe poly alpha-1,3-1,6-glucan synthesized by the glucosyltransferaseenzyme are alpha-1,3 linkages, (ii) at least 30% of the glycosidiclinkages of the poly alpha-1,3-1,6-glucan synthesized by theglucosyltransferase enzyme are alpha-1,6 linkages, and (iii) the polyalpha-1,3-1,6-glucan synthesized by the glucosyltransferase enzyme has aweight average degree of polymerization (DP_(w)) of at least 1000.

In a third embodiment, at least 60% of the glycosidic linkages of thepoly alpha-1,3-1,6-glucan synthesized by the glucosyltransferase enzymeare alpha-1,6 linkages.

In a fourth embodiment, the DP_(w) of the poly alpha-1,3-1,6-glucansynthesized by the glucosyltransferase enzyme is at least 10000.

In a fifth embodiment, the glucosyltransferase enzyme comprises theamino acid sequence of SEQ ID NO:2, SEQ ID NO:4, SEQ ID NO:6, SEQ IDNO:8, or SEQ ID NO:10.

In a sixth embodiment, the invention concerns a method for producingpoly alpha-1,3-1,6-glucan comprising the step of contacting at leastwater, sucrose, and a glucosyltransferase enzyme that synthesizes polyalpha-1,3-1,6-glucan. The glucosyltransferase enzyme comprises an aminoacid sequence that is at least 90% identical to SEQ ID NO:2, SEQ IDNO:4, SEQ ID NO:6, SEQ ID NO:8, or SEQ ID NO:10. The polyalpha-1,3-1,6-glucan produced in this method can optionally be isolated.

In a seventh embodiment, (i) at least 30% of the glycosidic linkages ofthe poly alpha-1,3-1,6-glucan synthesized by the glucosyltransferaseenzyme in the method are alpha-1,3 linkages, (ii) at least 30% of theglycosidic linkages of the poly alpha-1,3-1,6-glucan are alpha-1,6linkages, and (iii) the poly alpha-1,3-1,6-glucan has a DP_(w) of atleast 1000.

In an eighth embodiment, at least 60% of the glycosidic linkages of thepoly alpha-1,3-1,6-glucan synthesized by the glucosyltransferase enzymein the method are alpha-1,6 linkages.

In a ninth embodiment, the DP_(w) of poly alpha-1,3-1,6-glucansynthesized by the glucosyltransferase enzyme in the method is at least10000.

BRIEF DESCRIPTION OF THE SEQUENCES

TABLE 1 Summary of Nucleic Acid and Protein SEQ ID Numbers Nucleic acidProtein SEQ SEQ Description ID NO. ID NO. “4297 gtf”, Streptococcusoralis. DNA codon- 1 2 optimized for expression in E. coli. The first228 (1348 aa) amino acids of the protein are deleted compared to GENBANKIdentification No. 7684297, which discloses “glucosyltransferase”. 3 4“3298 gtf”, Streptococcus sp. C150. The first 209 (1242 aa) amino acidsof the protein are deleted compared to GENBANK Identification No.322373298, which discloses “glucosyltransferase-S”. “0544 gtf”,Streptococcus mutans. DNA codon- 5 6 optimized for expression in E.coli. The first 164 (1313 aa) amino acids of the protein are deletedcompared to GENBANK Identification No. 290580544, which discloses“glucosyltransferase-I”. “5618 gtf”, Streptococcus sanguinis. DNA codon-7 8 optimized for expression in E. coli. The first 223 (1348 aa) aminoacids of the protein are deleted compared to GENBANK Identification No.328945618, which discloses “glucosyltransferase-S”. “2379 gtf”,Streptococcus salivarius. DNA codon- 9 10 optimized for expression in E.coli. The first 203 (1247 aa) amino acids of the protein are deletedcompared to GENBANK Identification No. 662379, which discloses“glucosyltransferase”.

DETAILED DESCRIPTION OF THE INVENTION

The disclosures of all cited patent and non-patent literature areincorporated herein by reference in their entirety.

As used herein, the term “invention” or “disclosed invention” is notmeant to be limiting, but applies generally to any of the inventionsdefined in the claims or described herein. These terms are usedinterchangeably herein.

The term “glucan” herein refers to a polysaccharide of D-glucosemonomers that are linked by glycosidic linkages.

The terms “glycosidic linkage” and “glycosidic bond” are usedinterchangeably herein and refer to the type of covalent bond that joinsa carbohydrate molecule to another carbohydrate molecule. The term“alpha-1,3-glycosidic linkage” as used herein refers to the type ofcovalent bond that joins alpha-D-glucose molecules to each other throughcarbons 1 and 3 on adjacent alpha-D-glucose rings. The term“alpha-1,6-glycosidic linkage” as used herein refers to the type ofcovalent bond that joins alpha-D-glucose molecules to each other throughcarbons 1 and 6 on adjacent alpha-D-glucose rings. Herein,“alpha-D-glucose” will be referred to as “glucose.” All glycosidiclinkages disclosed herein are alpha-glycosidic linkages, except whereotherwise noted.

The glycosidic linkage profile of a poly alpha-1,3-1,6-glucan herein canbe determined using any method known in the art. For example, a linkageprofile can be determined using methods that use nuclear magneticresonance (NMR) spectroscopy (e.g., ¹³C NMR or ¹H NMR). These and othermethods that can be used are disclosed in Food Carbohydrates: Chemistry,Physical Properties, and Applications (S. W. Cui, Ed., Chapter 3, S. W.Cui, Structural Analysis of Polysaccharides, Taylor & Francis Group LLC,Boca Raton, Fla., 2005), which is incorporated herein by reference.

The terms “poly alpha-1,3-1,6-glucan”, “alpha-1,3-1,6-glucan polymer”,and “poly (alpha-1,3)(alpha-1,6) glucan” are used interchangeably herein(note that the order of the linkage denotations “1,3” and “1,6” in theseterms is of no moment). Poly alpha-1,3-1,6-glucan herein is a polymercomprising glucose monomeric units linked together by glycosidiclinkages, wherein at least about 30% of the glycosidic linkages arealpha-1,3-glycosidic linkages, and at least about 30% of the glycosidiclinkages are alpha-1,6-glycosidic linkages. Poly alpha-1,3-1,6-glucan isa type of polysaccharide containing a mixed glycosidic linkage content.The meaning of the term poly alpha-1,3-1,6-glucan in certain embodimentsherein excludes “alternan,” which is a glucan containing alpha-1,3linkages and alpha-1,6 linkages that consecutively alternate with eachother (U.S. Pat. No. 5,702,942, U.S. Pat. Appl. Publ. No. 2006/0127328).Alpha-1,3 and alpha-1,6 linkages that “consecutively alternate” witheach other can be visually represented by . . .G-1,3-G-1,6-G-1,3-G-1,6-G-1,3-G-1,6-G-1,3-G- . . . , for example, whereG represents glucose.

Poly alpha-1,3-1,6-glucan herein, for example, can be produced by aglucosyltransferase enzyme comprising an amino acid sequence that is atleast 90% identical to SEQ ID NO:2, SEQ ID NO:4, SEQ ID NO:6, SEQ IDNO:8, or SEQ ID NO:10. Such production can be from a gtf reactionherein.

The term “sucrose” herein refers to a non-reducing disaccharide composedof an alpha-D-glucose molecule and a beta-D-fructose molecule linked byan alpha-1,2-glycosidic bond. Sucrose is known commonly as table sugar.

The “molecular weight” of a poly alpha-1,3-1,6-glucan or polyalpha-1,3-1,6-glucan ether compound herein can be represented asnumber-average molecular weight (M_(n)) or as weight-average molecularweight (M_(w)). Alternatively, molecular weight can be represented asDaltons, grams/mole, DP_(w) (weight average degree of polymerization),or DP_(n) (number average degree of polymerization). Various means areknown in the art for calculating these molecular weight measurementssuch as with high-pressure liquid chromatography (HPLC), size exclusionchromatography (SEC), or gel permeation chromatography (GPC).

The terms “glucosyltransferase enzyme”, “gtf enzyme”, “gtf enzymecatalyst”, “gtf”, and “glucansucrase” are used interchangeably herein.The activity of a gtf enzyme herein catalyzes the reaction of thesubstrate sucrose to make the products poly alpha-1,3-1,6-glucan andfructose. Other products (byproducts) of a gtf reaction can includeglucose (where glucose is hydrolyzed from the glucosyl-gtf enzymeintermediate complex), various soluble oligosaccharides, and leucrose(where glucose of the glucosyl-gtf enzyme intermediate complex is linkedto fructose). Leucrose is a disaccharide composed of glucose andfructose linked by an alpha-1,5 linkage. Wild type forms ofglucosyltransferase enzymes generally contain (in the N-terminal toC-terminal direction) a signal peptide, a variable domain, a catalyticdomain, and a glucan-binding domain. A gtf herein is classified underthe glycoside hydrolase family 70 (GH70) according to the CAZy(Carbohydrate-Active EnZymes) database (Cantarel et al., Nucleic AcidsRes. 37:D233-238, 2009).

The terms “glucosyltransferase catalytic domain” and “catalytic domain”are used interchangeably herein and refer to the domain of aglucosyltransferase enzyme that provides polyalpha-1,3-1,6-glucan-producing activity to the glucosyltransferaseenzyme.

The terms “gtf reaction” and “enzymatic reaction” are usedinterchangeably herein and refer to a reaction that is performed by aglucosyltransferase enzyme. A “gtf reaction solution” as used hereingenerally refers to a solution comprising at least one activeglucosyltransferase enzyme in a solution comprising sucrose and water,and optionally other components. It is in a gtf reaction solution wherethe step of contacting water, sucrose and a glucosyltransferase enzymeis performed. The term “under suitable gtf reaction conditions” as usedherein, refers to gtf reaction conditions that support conversion ofsucrose to poly alpha-1,3-1,6-glucan via glucosyltransferase enzymeactivity. A gtf reaction herein is not naturally occurring.

The terms “percent by volume”, “volume percent”, “vol %” and “v/v %” areused interchangeably herein. The percent by volume of a solute in asolution can be determined using the formula: [(volume ofsolute)/(volume of solution)]×100%.

The terms “percent by weight”, “weight percentage (wt %)” and“weight-weight percentage (% w/w)” are used interchangeably herein.Percent by weight refers to the percentage of a material on a mass basisas it is comprised in a composition, mixture, or solution.

The terms “increased”, “enhanced” and “improved” are usedinterchangeably herein. These terms refer to a greater quantity oractivity such as a quantity or activity slightly greater than theoriginal quantity or activity, or a quantity or activity in large excesscompared to the original quantity or activity, and including allquantities or activities in between. Alternatively, these terms mayrefer to, for example, a quantity or activity that is at least 1%, 2%,3%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%,19% or 20% more than the quantity or activity for which the increasedquantity or activity is being compared.

The terms “polynucleotide”, “polynucleotide sequence”, and “nucleic acidsequence” are used interchangeably herein. These terms encompassnucleotide sequences and the like. A polynucleotide may be a polymer ofDNA or RNA that is single- or double-stranded, that optionally containssynthetic, non-natural or altered nucleotide bases. A polynucleotide maybe comprised of one or more segments of cDNA, genomic DNA, syntheticDNA, or mixtures thereof.

The term “gene” as used herein refers to a polynucleotide sequence thatexpresses a protein, and which may refer to the coding region alone ormay include regulatory sequences upstream and/or downstream to thecoding region (e.g., 5′ untranslated regions upstream of thetranscription start site of the coding region). A gene that is “native”or “endogenous” refers to a gene as found in nature with its ownregulatory sequences; this gene is located in its natural location inthe genome of an organism. “Chimeric gene” refers to any gene that isnot a native gene, comprising regulatory and coding sequences that arenot found together in nature. A “foreign” or “heterologous” gene refersto a gene that is introduced into the host organism by gene transfer.Foreign genes can comprise native genes inserted into a non-nativeorganism, native genes introduced into a new location within the nativehost, or chimeric genes. Polynucleotide sequences in certain embodimentsdisclosed herein are heterologous. A “transgene” is a gene that has beenintroduced into the genome by a transformation procedure. A“codon-optimized gene” is a gene having its frequency of codon usagedesigned to mimic the frequency of preferred codon usage of particularhost cell.

The term “recombinant” or “heterologous” as used herein refers to anartificial combination of two otherwise separate segments of sequence,e.g., by chemical synthesis or by the manipulation of isolated segmentsof nucleic acids by genetic engineering techniques. The terms“recombinant”, “transgenic”, “transformed”, “engineered” or “modifiedfor exogenous gene expression” are used interchangeably herein.

The term “transformation” as used herein refers to the transfer of anucleic acid molecule into a host organism. The nucleic acid moleculemay be a plasmid that replicates autonomously, or it may integrate intothe genome of the host organism. Host organisms containing a transformednucleic acid fragment(s) are “transgenic”, “recombinant”, or“transformed”, and can be referred to as “transformants”.

A native amino acid sequence or polynucleotide sequence is naturallyoccurring, whereas a non-native amino acid sequence or polynucleotidesequence does not occur in nature.

“Coding sequence” as used herein refers to a DNA sequence that codes fora specific amino acid sequence. “Regulatory sequences” as used hereinrefer to nucleotide sequences located upstream of the coding sequence'stranscription start site, 5′ untranslated regions and 3′ non-codingregions, and which may influence the transcription, RNA processing orstability, or translation of the associated coding sequence. Regulatorysequences may include promoters, enhancers, silencers, 5′ untranslatedleader sequence, introns, polyadenylation recognition sequences, RNAprocessing sites, effector binding sites, stem-loop structures and otherelements involved in regulation of gene expression.

The terms “sequence identity” or “identity” as used herein with respectto polynucleotide or polypeptide sequences refer to the nucleic acidbases or amino acid residues in two sequences that are the same whenaligned for maximum correspondence over a specified comparison window.Thus, “percentage of sequence identity” or “percent identity” refers tothe value determined by comparing two optimally aligned sequences over acomparison window, wherein the portion of the polynucleotide orpolypeptide sequence in the comparison window may comprise additions ordeletions (i.e., gaps) as compared to the reference sequence (which doesnot comprise additions or deletions) for optimal alignment of the twosequences. The percentage is calculated by determining the number ofpositions at which the identical nucleic acid base or amino acid residueoccurs in both sequences to yield the number of matched positions,dividing the number of matched positions by the total number ofpositions in the window of comparison and multiplying the results by 100to yield the percentage of sequence identity.

The Basic Local Alignment Search Tool (BLAST) algorithm, which isavailable online at the National Center for Biotechnology Information(NCBI) website, may be used, for example, to measure percent identitybetween or among two or more of the polynucleotide sequences (BLASTNalgorithm) or polypeptide sequences (BLASTP algorithm) disclosed herein.Alternatively, percent identity between sequences may be performed usinga Clustal algorithm (e.g., ClustalW or ClustalV). For multiplealignments using a Clustal method of alignment, the default values maycorrespond to GAP PENALTY=10 and GAP LENGTH PENALTY=10. Defaultparameters for pairwise alignments and calculation of percent identityof protein sequences using a Clustal method may be KTUPLE=1, GAPPENALTY=3, WINDOW=5 and DIAGONALS SAVED=5. For nucleic acids, theseparameters may be KTUPLE=2, GAP PENALTY=5, WINDOW=4 and DIAGONALSSAVED=4. Alternatively still, percent identity between sequences may beperformed using an EMBOSS algorithm (e.g., needle) with parameters suchas GAP OPEN=10, GAP EXTEND=0.5, END GAP PENALTY=false, END GAP OPEN=10,END GAP EXTEND=0.5 using a BLOSUM matrix (e.g., BLOSUM62).

Various polypeptide amino acid sequences and polynucleotide sequencesare disclosed herein as features of certain embodiments. Variants ofthese sequences that are at least about 70-85%, 85-90%, or 90%-95%identical to the sequences disclosed herein can be used. Alternatively,a variant amino acid sequence or polynucleotide sequence can have atleast 70%, 71%, 72%, 73%, 74%, 75%, 76%, 77%, 78%, 79%, 80%, 81%, 82%,83%, 84%, 85%, 86%, 87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%,97%, 98% or 99% identity with a sequence disclosed herein. The variantamino acid sequence or polynucleotide sequence may have the samefunction/activity of the disclosed sequence, or at least about 85%, 86%,87%, 88%, 89%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% ofthe function/activity of the disclosed sequence.

The term “isolated” as used in certain embodiments refers to anycellular component that has been completely or partially purified fromits native source (e.g., an isolated polynucleotide or polypeptidemolecule). In some instances, an isolated polynucleotide or polypeptidemolecule is part of a greater composition, buffer system or reagent mix.For example, an isolated polynucleotide or polypeptide molecule can becomprised within a cell or organism in a heterologous manner. Anotherexample is an isolated glucosyltransferase enzyme.

The terms “poly alpha-1,3-1,6-glucan ether compound”, “polyalpha-1,3-1,6-glucan ether”, and “poly alpha-1,3-1,6-glucan etherderivative” are used interchangeably herein. A poly alpha-1,3-1,6-glucanether compound herein is a poly alpha-1,3-1,6-glucan that has beenetherified with one or more organic groups such that the compound has adegree of substitution (DoS) with the organic group of about 0.05 toabout 3.0. Such etherification occurs at one or more hydroxyl groups ofat least 30% of the glucose monomeric units of the polyalpha-1,3-1,6-glucan.

A poly alpha-1,3-1,6-glucan ether compound is termed an “ether” hereinby virtue of comprising the substructure —C_(G)—O—C—, where “—C_(G)—”represents a carbon atom of a glucose monomeric unit of a polyalpha-1,3-1,6-glucan ether compound (where such carbon atom was bondedto a hydroxyl group [—OH] in the poly alpha-1,3-1,6-glucan precursor ofthe ether), and where “—C—” is a carbon atom of the organic group. Thus,for example, with regard to a glucose monomeric unit (G) involved in-1,3-G-1,3- within an ether herein, C_(G) atoms 2, 4 and/or 6 of theglucose (G) may independently be linked to an OH group or be in etherlinkage to an organic group. Similarly, for example, with regard to aglucose monomeric unit (G) involved in -1,3-G-1,6- within an etherherein, C_(G) atoms 2, 4 and/or 6 of the glucose (G) may independentlybe linked to an OH group or be in ether linkage to an organic group.Also, for example, with regard to a glucose monomeric unit (G) involvedin -1,6-G-1,6- within an ether herein, C_(G) atoms 2, 3 and/or 4 of theglucose (G) may independently be linked to an OH group or be in etherlinkage to an organic group. Similarly, for example, with regard to aglucose monomeric unit (G) involved in -1,6-G-1,3- within an etherherein, C_(G) atoms 2, 3 and/or 4 of the glucose (G) may independentlybe linked to an OH group or be in ether linkage to an organic group.

It would be understood that a “glucose” monomeric unit of a polyalpha-1,3-1,6-glucan ether compound herein typically has one or moreorganic groups in ether linkage. Thus, such a glucose monomeric unit canalso be referred to as an etherized glucose monomeric unit.

Poly alpha-1,3-1,6-glucan ether compounds disclosed herein aresynthetic, man-made compounds. Likewise, compositions comprising polyalpha-1,3-1,6-glucan (e.g., isolated poly alpha-1,3-1,6-glucan) aresynthetic, man-made compounds.

An “organic group” group as used herein refers to a chain of one or morecarbons that (i) has the formula —C_(n)H_(2n+1) (i.e., an alkyl group,which is completely saturated) or (ii) is mostly saturated but has oneor more hydrogens substituted with another atom or functional group(i.e., a “substituted alkyl group”). Such substitution may be with oneor more hydroxyl groups, oxygen atoms (thereby forming an aldehyde orketone group), carboxyl groups, or other alkyl groups. Thus, asexamples, an organic group herein can be an alkyl group, carboxy alkylgroup, or hydroxy alkyl group.

A “carboxy alkyl” group herein refers to a substituted alkyl group inwhich one or more hydrogen atoms of the alkyl group are substituted witha carboxyl group. A “hydroxy alkyl” group herein refers to a substitutedalkyl group in which one or more hydrogen atoms of the alkyl group aresubstituted with a hydroxyl group.

A “halide” herein refers to a compound comprising one or more halogenatoms (e.g., fluorine, chlorine, bromine, iodine). A halide herein canrefer to a compound comprising one or more halide groups such asfluoride, chloride, bromide, or iodide. A halide group may serve as areactive group of an etherification agent.

The terms “reaction”, “reaction composition”, and “etherificationreaction” are used interchangeably herein and refer to a reactioncomprising at least poly alpha-1,3-1,6-glucan and an etherificationagent. These components are typically mixed (e.g., resulting in aslurry) and/or dissolved in a solvent (organic and/or aqueous)comprising alkali hydroxide. A reaction is placed under suitableconditions (e.g., time, temperature) for the etherification agent toetherify one or more hydroxyl groups of the glucose units of polyalpha-1,3-1,6-glucan with an organic group, thereby yielding a polyalpha-1,3-1,6-glucan ether compound.

The term “alkaline conditions” herein refers to a solution or mixture pHof at least 11 or 12. Alkaline conditions can be prepared by any meansknown in the art, such as by dissolving an alkali hydroxide in asolution or mixture.

The terms “etherification agent” and “alkylation agent” are usedinterchangeably herein. An etherification agent herein refers to anagent that can be used to etherify one or more hydroxyl groups ofglucose units of poly alpha-1,3-1,6-glucan with an organic group. Anetherification agent thus comprises an organic group.

The term “poly alpha-1,3-1,6-glucan slurry” herein refers to an aqueousmixture comprising the components of a glucosyltransferase enzymaticreaction such as poly alpha-1,3-1,6-glucan, sucrose, one or moreglucosyltransferase enzymes, glucose and fructose.

The term “poly alpha-1,3-1,6-glucan wet cake” herein refers to polyalpha-1,3-1,6-glucan that has been separated from a slurry and washedwith water or an aqueous solution. Poly alpha-1,3-1,6-glucan is notdried when preparing a wet cake.

The term “degree of substitution” (DoS) as used herein refers to theaverage number of hydroxyl groups substituted in each monomeric unit(glucose) of a poly alpha-1,3-1,6-glucan ether compound. Since there areat most three hydroxyl groups in a glucose monomeric unit in a polyalpha-1,3-1,6-glucan herein (which is believed to be linear orbranched), the degree of substitution in a poly alpha-1,3-1,6-glucanether compound herein can be no higher than 3.

The term “molar substitution” (M.S.) as used herein refers to the molesof an organic group per monomeric unit of a poly alpha-1,3-1,6-glucanether compound. Alternatively, M.S. can refer to the average moles ofetherification agent used to react with each monomeric unit in polyalpha-1,3-1,6-glucan (M.S. can thus describe the degree ofderivatization with an etherification agent). It is noted that the M.S.value for poly alpha-1,3-1,6-glucan may have no upper limit. Forexample, when an organic group containing a hydroxyl group (e.g.,hydroxyethyl or hydroxypropyl) has been etherified to polyalpha-1,3-1,6-glucan, the hydroxyl group of the organic group mayundergo further reaction, thereby coupling more of the organic group tothe poly alpha-1,3-1,6-glucan.

The term “crosslink” herein refers to a chemical bond, atom, or group ofatoms that connects two adjacent atoms in one or more polymer molecules.It should be understood that, in a composition comprising crosslinkedpoly alpha-1,3-1,6-glucan ether, crosslinks can be between at least twopoly alpha-1,3-1,6-glucan ether molecules (i.e., intermolecularcrosslinks); there can also be intramolecular crosslinking. A“crosslinking agent” as used herein is an atom or compound that cancreate crosslinks.

The terms “hydrocolloid” and “hydrogel” are used interchangeably herein.A hydrocolloid refers to a colloid system in which water is thedispersion medium. A “colloid” herein refers to a substance that ismicroscopically dispersed throughout another substance. Therefore, ahydrocolloid herein can also refer to a dispersion, mixture, or solutionof poly alpha-1,3-1,6-glucan and/or one or more polyalpha-1,3-1,6-glucan ether compounds in water or aqueous solution.

The term “aqueous solution” herein refers to a solution in which thesolvent is water. Poly alpha-1,3-1,6-glucan and/or one or more polyalpha-1,3-1,6-glucan ether compounds herein can be dispersed, mixed,and/or dissolved in an aqueous solution. An aqueous solution can serveas the dispersion medium of a hydrocolloid herein.

The term “viscosity” as used herein refers to the measure of the extentto which a fluid or an aqueous composition such as a hydrocolloidresists a force tending to cause it to flow. Various units of viscositythat can be used herein include centipoise (cPs) and Pascal-second(Pa·s). A centipoise is one one-hundredth of a poise; one poise is equalto 0.100 kg·m⁻¹·s⁻¹. Thus, the terms “viscosity modifier” and“viscosity-modifying agent” as used herein refer to anything that canalter/modify the viscosity of a fluid or aqueous composition.

The term “shear thinning behavior” as used herein refers to a decreasein the viscosity of the hydrocolloid or aqueous solution as shear rateincreases. The term “shear thickening behavior” as used herein refers toan increase in the viscosity of the hydrocolloid or aqueous solution asshear rate increases. “Shear rate” herein refers to the rate at which aprogressive shearing deformation is applied to the hydrocolloid oraqueous solution. A shearing deformation can be applied rotationally.

The term “contacting” as used herein with respect to methods ofincreasing the viscosity of an aqueous composition refers to any actionthat results in bringing together an aqueous composition and a polyalpha-1,3-1,6-glucan ether compound. Contacting can be performed by anymeans known in the art, such as dissolving, mixing, shaking, orhomogenization, for example.

Embodiments of the disclosed invention concern a reaction solutioncomprising water, sucrose, and a glucosyltransferase enzyme thatsynthesizes poly alpha-1,3-1,6-glucan. The glucosyltransferase enzymecomprises an amino acid sequence that is at least 90% identical to SEQID NO:2, SEQ ID NO:4, SEQ ID NO:6, SEQ ID NO:8, or SEQ ID NO:10.Significantly, these enzymes can synthesize poly alpha-1,3-1,6-glucanthat can be derivatized into ethers having enhanced viscositymodification qualities.

Regarding poly alpha-1,3-1,6-glucan produced in a reaction solutionherein:

(i) at least 30% of the glycosidic linkages of the polyalpha-1,3-1,6-glucan are alpha-1,3 linkages,

(ii) at least 30% of the glycosidic linkages of the polyalpha-1,3-1,6-glucan are alpha-1,6 linkages, and

(iii) the poly alpha-1,3-1,6-glucan has a weight average degree ofpolymerization (DP_(w)) of at least 1000.

At least 30% of the glycosidic linkages of poly alpha-1,3-1,6-glucansynthesized by a glucosyltransferase enzyme herein are alpha-1,3linkages, and at least 30% of the glycosidic linkages are alpha-1,6linkages. Alternatively, the percentage of alpha-1,3 linkages can be atleast 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, 40%, 41%, 42%, 43%,44%, 45%, 46%, 47%, 48%, 49%, 50%, 51%, 52%, 53%, 54%, 55%, 56%, 57%,58%, 59%, 60%, 61%, 62%, 63%, or 64%. Alternatively still, thepercentage of alpha-1,6 linkages can be at least 31%, 32%, 33%, 34%,35%, 36%, 37%, 38%, 39%, 40%, 41%, 42%, 43%, 44%, 45%, 46%, 47%, 48%,49%, 50%, 51%, 52%, 53%, 54%, 55%, 56%, 57%, 58%, 59%, 60%, 61%, 62%,63%, 64%, 65%, 66%, 67%, 68%, or 69%.

A poly alpha-1,3-1,6-glucan synthesized by a glucosyltransferase enzymeherein can have any one the aforementioned percentages of alpha-1,3linkages and any one of the aforementioned percentages of alpha-1,6linkages, just so long that the total of the percentages is not greaterthan 100%. For example, the poly alpha-1,3-1,6-glucan can have (i) anyone of 30%, 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, or 40%(30%-40%) alpha-1,3 linkages and (ii) any one of 60%, 61%, 62%, 63%,64%, 65%, 66%, 67%, 68%, or 69% (60%-69%) alpha-1,6 linkages, just solong that the total of the percentages is not greater than 100%.Non-limiting examples include poly alpha-1,3-1,6-glucan with 31%alpha-1,3 linkages and 67% alpha-1,6 linkages. Other examples ofalpha-1,3 and alpha-1,6 linkage profiles are provided in Table 2. Incertain embodiments, at least 60% of the glycosidic linkages of polyalpha-1,3-1,6-glucan produced in a gtf reaction solution herein arealpha-1,6 linkages.

Poly alpha-1,3-1,6-glucan synthesized by a glucosyltransferase enzymeherein can have, for example, less than 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%,2%, or 1% of glycosidic linkages other than alpha-1,3 and alpha-1,6. Inanother embodiment, poly alpha-1,3-1,6-glucan only has alpha-1,3 andalpha-1,6 linkages.

The backbone of a poly alpha-1,3-1,6-glucan synthesized by aglucosyltransferase enzyme herein can be linear/unbranched.Alternatively, there can be branches in the poly alpha-1,3-1,6-glucan. Apoly alpha-1,3-1,6-glucan in certain embodiments can thus have no branchpoints or less than about 30%, 29%, 28%, 27%, 26%, 25%, 24%, 23%, 22%,21%, 20%, 19%, 18%, 17%, 16%, 15%, 14%, 13%, 12%, 11%, 10%, 9%, 8%, 7%,6%, 5%, 4%, 3%, 2%, or 1% branch points as a percent of the glycosidiclinkages in the polymer.

In certain embodiments of the disclosed invention, a glucosyltransferaseenzyme can synthesize poly alpha-1,3-1,6-glucan comprising alpha-1,3linkages and alpha-1,6 linkages that do not consecutively alternate witheach other. For the following discussion, consider that . . .G-1,3-G-1,6-G-1,3-G-1,6-G-1,3-G- . . . (where G represents glucose)represents a stretch of six glucose monomeric units linked byconsecutively alternating alpha-1,3 linkages and alpha-1,6 linkages.Alternatively, poly alpha-1,3-1,6-glucan synthesized by aglucosyltransferase enzyme herein can comprise, for example, less than2, 3, 4, 5, 6, 7, 8, 9, 10, or more glucose monomeric units that arelinked consecutively with alternating alpha-1,3 and alpha-1,6 linkages.

The molecular weight of poly alpha-1,3-1,6-glucan synthesized by aglucosyltransferase enzyme herein can be measured as DP_(w) (weightaverage degree of polymerization) or DP_(n) (number average degree ofpolymerization). Alternatively, molecular weight can be measured inDaltons or grams/mole. It may also be useful to refer to thenumber-average molecular weight (M_(n)) or weight-average molecularweight (M_(w)) of the poly alpha-1,3-1,6-glucan.

Poly alpha-1,3-1,6-glucan synthesized by a glucosyltransferase enzymeherein has a DP_(w) of at least about 1000. For example, the DP_(w) ofthe poly alpha-1,3-1,6-glucan can be at least about 10000.Alternatively, the DP_(w) can be at least about 1000 to about 15000.Alternatively still, the DP_(w) can be at least about 1000, 2000, 3000,4000, 5000, 6000, 7000, 8000, 9000, 10000, 11000, 12000, 13000, 14000,or 15000 (or any integer between 1000 and 15000), for example. Giventhat poly alpha-1,3-1,6-glucan herein has a DP_(w) of at least about1000, such a glucan polymer is typically, but not necessarily,water-insoluble.

In certain embodiments of the disclosed gtf reaction solution, polyalpha-1,3-1,6-glucan can have an M_(w) of at least about 50000, 100000,200000, 300000, 400000, 500000, 600000, 700000, 800000, 900000, 1000000,1100000, 1200000, 1300000, 1400000, 1500000, or 1600000 (or any integerbetween 50000 and 1600000), for example.

A glucosyltransferase enzyme herein may be obtained from any microbialsource, such as a bacteria or fungus. Examples of bacterialglucosyltransferase enzymes are those derived from a Streptococcusspecies, Leuconostoc species or Lactobacillus species. Examples ofStreptococcus species include S. salivarius, S. sobrinus, S.dentirousetti, S. downei, S. mutans, S. oralis, S. gallolyticus and S.sanguinis. Examples of Leuconostoc species include L. mesenteroides, L.amelibiosum, L. argentinum, L. carnosum, L. citreum, L. cremoris, L.dextranicum and L. fructosum. Examples of Lactobacillus species includeL. acidophilus, L. delbrueckii, L. helveticus, L. salivarius, L. casei,L. curvatus, L. plantarum, L. sakei, L. brevis, L. buchneri, L.fermentum and L. reuteri.

A glucosyltransferase enzyme herein can comprise, or consist of, anamino acid sequence that is at least 90% identical to SEQ ID NO:2, SEQID NO:4, SEQ ID NO:6, SEQ ID NO:8, or SEQ ID NO:10, wherein theglucosyltransferase enzyme has activity. Alternatively, aglucosyltransferase enzyme can comprise, or consist of, an amino acidsequence that is at least 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99%identical to SEQ ID NO:4, SEQ ID NO:20, SEQ ID NO:28, or SEQ ID NO:30,wherein the glucosyltransferase enzyme has activity. Alternativelystill, a glucosyltransferase enzyme can comprise, or consist of, SEQ IDNO:2, SEQ ID NO:4, SEQ ID NO:6, SEQ ID NO:8, or SEQ ID NO:10.

Given that certain amino acids share similar structural and/or chargefeatures with each other (i.e., conserved), one or more amino acids ofthe disclosed gtf enzyme sequences may be substituted with a conservedamino acid residue (“conservative amino acid substitution”) as follows:

-   -   1. The following small aliphatic, nonpolar or slightly polar        residues can substitute for each other: Ala (A), Ser (S), Thr        (T), Pro (P), Gly (G);    -   2. The following polar, negatively charged residues and their        amides can substitute for each other: Asp (D), Asn (N), Glu (E),        Gln (Q);    -   3. The following polar, positively charged residues can        substitute for each other: His (H), Arg (R), Lys (K);    -   4. The following aliphatic, nonpolar residues can substitute for        each other: Ala (A), Leu (L), Ile (I), Val (V), Cys (C), Met        (M); and    -   5. The following large aromatic residues can substitute for each        other: Phe (F), Tyr (Y), Trp (W).

Examples of glucosyltransferase enzymes for use in a gtf reactionsolution may be any of the amino acid sequences disclosed herein andthat further include 1-300 (or any integer there between) residues onthe N-terminus and/or C-terminus. Such additional residues may be from acorresponding wild type sequence from which the glucosyltransferaseenzyme is derived, or may be another sequence such as an epitope tag (ateither N- or C-terminus) or a heterologous signal peptide (atN-terminus), for example.

The amino acid sequence of a glucosyltransferase enzyme herein can beencoded by the polynucleotide sequence provided in SEQ ID NO:1, SEQ IDNO:3, SEQ ID NO:5, SEQ ID NO:7, or SEQ ID NO:9, for example.Alternatively, such an amino acid sequence can be encoded by apolynucleotide sequence that is at least 90%, 91%, 92%, 93%, 94%, 95%,96%, 97%, 98%, or 99% identical to SEQ ID NO:1, SEQ ID NO:3, SEQ IDNO:5, SEQ ID NO:7, or SEQ ID NO:9.

One or more different glucosyltransferase enzymes may be used topractice the disclosed invention. The glucosyltransferase enzyme doesnot have, or has very little (less than 1%), alternansucrase activity,for example.

A glucosyltransferase enzyme herein can be primer-independent orprimer-dependent. Primer-independent glucosyltransferase enzymes do notrequire the presence of a primer to perform glucan synthesis. Aprimer-dependent glucosyltransferase enzyme requires the presence of aninitiating molecule in the reaction solution to act as a primer for theenzyme during glucan polymer synthesis. The term “primer” as used hereinrefers to any molecule that can act as the initiator for aglucosyltransferase enzyme. Oligosaccharides and polysaccharides canserve a primers, for example. Primers that can be used in certainembodiments include dextran and other carbohydrate-based primers, suchas hydrolyzed glucan, for example. U.S. Appl. Publ. No. 2013/0244287,which is incorporated herein by reference, discloses preparation ofhydrolyzed glucan using poly alpha-1,3-glucan as the starting material.Dextran for use as a primer can be dextran T10 (i.e., dextran having amolecular weight of 10 kD), for example. Alternatively, dextran primercan have a molecular weight of about 2, 4, 6, 8, 10, 12, 14, 16, 18, 20,or 25 kD, for example.

A glucosyltransferase enzyme of the disclosed invention may be producedby any means known in the art. For example, the glucosyltransferaseenzyme may be produced recombinantly in a heterologous expressionsystem, such as a microbial heterologous expression system. Examples ofheterologous expression systems include bacterial (e.g., E. coli such asTOP10 or MG1655; Bacillus sp.) and eukaryotic (e.g., yeasts such asPichia sp. and Saccharomyces sp.) expression systems.

A glucosyltransferase enzyme described herein may be used in anypurification state (e.g., pure or non-pure). For example, theglucosyltransferase enzyme may be purified and/or isolated prior to itsuse. Examples of glucosyltransferase enzymes that are non-pure includethose in the form of a cell lysate. A cell lysate or extract may beprepared from a bacteria (e.g., E. coli) used to heterologously expressthe enzyme. For example, the bacteria may be subjected to disruptionusing a French pressure cell. In alternative embodiments, bacteria maybe homogenized with a homogenizer (e.g., APV, Rannie, Gaulin). Aglucosyltransferase enzyme is typically soluble in these types ofpreparations. A bacterial cell lysate, extract, or homogenate herein maybe used at about 0.15-0.3% (v/v) in a reaction solution for producingpoly alpha-1,3-1,6-glucan from sucrose.

A heterologous gene expression system in certain embodiments may be onethat is designed for protein secretion. The glucosyltransferase enzymecomprises a signal peptide (signal sequence) in such embodiments. Thesignal peptide may be either its native signal peptide or a heterologoussignal peptide.

The activity of a glucosyltransferase enzyme herein can be determinedusing any method known in the art. For example, glucosyltransferaseenzyme activity can be determined by measuring the production ofreducing sugars (fructose and glucose) in a reaction solution containingsucrose (˜50 g/L), dextran T10 (˜1 mg/mL) and potassium phosphate buffer(˜pH 6.5, 50 mM), where the solution is held at ˜22-25° C. for ˜24-30hours. The reducing sugars can be measured by adding 0.01 mL of thereaction solution to a mixture containing ˜1 N NaOH and ˜0.1%triphenyltetrazolium chloride and then monitoring the increase inabsorbance at OD_(480nm) for ˜five minutes.

The temperature of a gtf reaction solution herein can be controlled, ifdesired. In certain embodiments, the temperature is between about 5° C.to about 50° C. The temperature in certain other embodiments is betweenabout 20° C. to about 40° C. Alternatively, the temperature may be about20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37,38, 39, or 40° C.

The temperature of a gtf reaction solution herein may be maintainedusing various means known in the art. For example, the temperature canbe maintained by placing the vessel containing the reaction solution inan air or water bath incubator set at the desired temperature.

The initial concentration of sucrose in a gtf reaction solution hereincan be about 20 g/L to about 400 g/L, for example. Alternatively, theinitial concentration of sucrose can be about 75 g/L to about 175 g/L,or from about 50 g/L to about 150 g/L. Alternatively still, the initialconcentration of sucrose can be about 40, 50, 60, 70, 80, 90, 100, 110,120, 130, 140, 150, or 160 g/L (or any integer between 40 and 160 g/L),for example. “Initial concentration of sucrose” refers to the sucroseconcentration in a gtf reaction solution just after all the reactionsolution components have been added (water, sucrose, gtf enzyme).

Any grade of sucrose can be used in a reaction solution disclosedherein. For example, the sucrose can be highly pure (≧99.5%), have apurity of at least 99.0%, or be reagent grade sucrose. Sucrose for useherein may be derived from any renewable sugar source such as sugarcane, sugar beets, cassava, sweet sorghum, or corn. The sucrose can beprovided in any form such as crystalline form or non-crystalline form(e.g., syrup or cane juice).

The pH of a gtf reaction solution in certain embodiments can be betweenabout 4.0 to about 8.0. Alternatively, the pH can be about 4.0, 4.5,5.0, 5.5, 6.0, 6.5, 7.0, 7.5, or 8.0. The pH can be adjusted orcontrolled by the addition or incorporation of a suitable buffer,including but not limited to: phosphate, tris, citrate, or a combinationthereof. Buffer concentration in a gtf reaction solution can be from 0mM to about 100 mM, or about 10, 20, or 50 mM, for example.

The disclosed invention also concerns a method for producing polyalpha-1,3-1,6-glucan comprising the step of contacting at least water,sucrose, and a glucosyltransferase enzyme that synthesizes polyalpha-1,3-1,6-glucan. The glucosyltransferase enzyme comprises an aminoacid sequence that is at least 90% identical to SEQ ID NO:2, SEQ IDNO:4, SEQ ID NO:6, SEQ ID NO:8, or SEQ ID NO:10. Polyalpha-1,3-1,6-glucan is produced in the contacting step. This polyalpha-1,3-1,6-glucan can optionally be isolated.

The contacting step in a method herein of producing polyalpha-1,3-1,6-glucan can comprise providing a gtf reaction solutioncomprising water, sucrose and any glucosyltransferase enzyme disclosedherein. It would be understood that, as the glucosyltransferase enzymesynthesizes poly alpha-1,3-1,6-glucan, the reaction solution typicallybecomes a reaction mixture given that insoluble polyalpha-1,3-1,6-glucan falls out of solution as indicated by clouding ofthe reaction. The contacting step of the disclosed method can beperformed in any number of ways. For example, the desired amount ofsucrose can first be dissolved in water (optionally, other componentsmay also be added at this stage of preparation, such as buffercomponents), followed by addition of the glucosyltransferase enzyme. Thesolution may be kept still, or agitated via stirring or orbital shaking,for example. The reaction can be, and typically is, cell-free.

Completion of a gtf reaction in certain embodiments can be determinedvisually (e.g., no more accumulation of precipitated polyalpha-1,3-1,6-glucan) and/or by measuring the amount of sucrose left inthe solution (residual sucrose), where a percent sucrose consumption ofover about 90% can indicate reaction completion. Typically, a reactionof the disclosed process can take about 12, 18, 24, 30, 36, 48, 60, 72,84, or 96 hours to complete. Reaction time may depend, for example, oncertain parameters such as the amount of sucrose and glucosyltransferaseenzyme used in the reaction.

The yield of poly alpha-1,3-1,6-glucan produced in a gtf reaction incertain embodiments herein can be at least about 4%, 5%, 6%, 7%, or 8%,based on the weight of the sucrose used in the reaction solution.

Poly alpha-1,3-1,6-glucan produced in the disclosed method mayoptionally be isolated. For example, insoluble poly alpha-1,3-1,6-glucanmay be separated by centrifugation or filtration. In doing so, the polyalpha-1,3-1,6-glucan is separated from the rest of the reactionsolution, which may comprise water, fructose and certain byproducts(e.g., leucrose, soluble oligosaccharides). This solution may alsocomprise glucose monomer and residual sucrose.

The linkage profile and/or molecular weight of poly alpha-1,3-1,6-glucanproduced in a gtf reaction herein can be any of those disclosed above.For example, (i) at least 30% of the glycosidic linkages are alpha-1,3linkages, (ii) at least 30% of the glycosidic linkages are alpha-1,6linkages, and (iii) the poly alpha-1,3-1,6-glucan has a DP_(w) of atleast 1000. Poly alpha-1,3-1,6-glucan produced in a gtf reaction canhave at least 60% alpha-1,6 linkages, and/or have a DP_(w) of at leastabout 10000.

Embodiments of the disclosed invention concern a composition comprisingpoly alpha-1,3-1,6-glucan, wherein:

(i) at least 30% of the glycosidic linkages of the polyalpha-1,3-1,6-glucan are alpha-1,3 linkages,

(ii) at least 30% of the glycosidic linkages of the polyalpha-1,3-1,6-glucan are alpha-1,6 linkages,

(iii) the poly alpha-1,3-1,6-glucan has a weight average degree ofpolymerization (DP_(w)) of at least 1000; and

(iv) the alpha-1,3 linkages and alpha-1,6 linkages of the polyalpha-1,3-1,6-glucan do not consecutively alternate with each other.

Significantly, poly alpha-1,3-1,6-glucan disclosed herein can bederivatized into ethers having enhanced viscosity modificationqualities.

At least 30% of the glycosidic linkages of poly alpha-1,3-1,6-glucandisclosed herein are alpha-1,3 linkages, and at least 30% of theglycosidic linkages of the poly alpha-1,3-1,6-glucan are alpha-1,6linkages. Alternatively, the percentage of alpha-1,3 linkages in polyalpha-1,3-1,6-glucan herein can be at least 31%, 32%, 33%, 34%, 35%,36%, 37%, 38%, 39%, 40%, 41%, 42%, 43%, 44%, 45%, 46%, 47%, 48%, 49%,50%, 51%, 52%, 53%, 54%, 55%, 56%, 57%, 58%, 59%, 60%, 61%, 62%, 63%, or64%. Alternatively still, the percentage of alpha-1,6 linkages in polyalpha-1,3-1,6-glucan herein can be at least 31%, 32%, 33%, 34%, 35%,36%, 37%, 38%, 39%, 40%, 41%, 42%, 43%, 44%, 45%, 46%, 47%, 48%, 49%,50%, 51%, 52%, 53%, 54%, 55%, 56%, 57%, 58%, 59%, 60%, 61%, 62%, 63%,64%, 65%, 66%, 67%, 68%, or 69%.

A poly alpha-1,3-1,6-glucan of the invention can have any one theaforementioned percentages of alpha-1,3 linkages and any one of theaforementioned percentages of alpha-1,6 linkages, just so long that thetotal of the percentages is not greater than 100%. For example, polyalpha-1,3-1,6-glucan herein can have (i) any one of 30%, 31%, 32%, 33%,34%, 35%, 36%, 37%, 38%, 39%, or 40% (30%-40%) alpha-1,3 linkages and(ii) any one of 60%, 61%, 62%, 63%, 64%, 65%, 66%, 67%, 68%, or 69%(60%-69%) alpha-1,6 linkages, just so long that the total of thepercentages is not greater than 100%. Non-limiting examples include polyalpha-1,3-1,6-glucan with 31% alpha-1,3 linkages and 67% alpha-1,6linkages. Other examples of alpha-1,3 and alpha-1,6 linkage profiles areprovided in Table 2. In certain embodiments, at least 60% of theglycosidic linkages of the poly alpha-1,3-1,6-glucan are alpha-1,6linkages.

A poly alpha-1,3-1,6-glucan of the invention can have, for example, lessthan 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, or 1% of glycosidic linkagesother than alpha-1,3 and alpha-1,6. In another embodiment, a polyalpha-1,3-1,6-glucan only has alpha-1,3 and alpha-1,6 linkages.

The backbone of a poly alpha-1,3-1,6-glucan disclosed herein can belinear/unbranched. Alternatively, there can be branches in the polyalpha-1,3-1,6-glucan. A poly alpha-1,3-1,6-glucan in certain embodimentscan thus have no branch points or less than about 30%, 29%, 28%, 27%,26%, 25%, 24%, 23%, 22%, 21%, 20%, 19%, 18%, 17%, 16%, 15%, 14%, 13%,12%, 11%, 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, or 1% branch points as apercent of the glycosidic linkages in the polymer.

The alpha-1,3 linkages and alpha-1,6 linkages of a polyalpha-1,3-1,6-glucan in the disclosed composition do not consecutivelyalternate with each other. For the following discussion, consider that .. . G-1,3-G-1,6-G-1,3-G-1,6-G-1,3-G- . . . (where G represents glucose)represents a stretch of six glucose monomeric units linked byconsecutively alternating alpha-1,3 linkages and alpha-1,6 linkages.Poly alpha-1,3-1,6-glucan in certain embodiments herein comprises lessthan 2, 3, 4, 5, 6, 7, 8, 9, 10, or more glucose monomeric units thatare linked consecutively with alternating alpha-1,3 and alpha-1,6linkages.

The molecular weight of a poly alpha-1,3-1,6-glucan disclosed herein canbe measured as DP_(w) (weight average degree of polymerization) orDP_(n) (number average degree of polymerization). Alternatively,molecular weight can be measured in Daltons or grams/mole. It may alsobe useful to refer to the number-average molecular weight (M_(n)) orweight-average molecular weight (M_(w)) of the polyalpha-1,3-1,6-glucan.

A poly alpha-1,3-1,6-glucan herein has a DP_(w) of at least about 1000.For example, the DP_(w) of the poly alpha-1,3-1,6-glucan can be at leastabout 10000. Alternatively, the DP_(w) can be at least about 1000 toabout 15000. Alternatively still, the DP_(w) can be at least about 1000,2000, 3000, 4000, 5000, 6000, 7000, 8000, 9000, 10000, 11000, 12000,13000, 14000, or 15000 (or any integer between 1000 and 15000), forexample. Given that a poly alpha-1,3-1,6-glucan herein has a DP_(w) ofat least about 1000, such a glucan polymer is typically, but notnecessarily, water-insoluble.

A poly alpha-1,3-1,6-glucan herein can have an M_(w) of at least about50000, 100000, 200000, 300000, 400000, 500000, 600000, 700000, 800000,900000, 1000000, 1100000, 1200000, 1300000, 1400000, 1500000, or 1600000(or any integer between 50000 and 1600000), for example. The M_(w) incertain embodiments is at least about 1000000.

A poly alpha-1,3-1,6-glucan herein can comprise at least 6 glucosemonomeric units, for example. Alternatively, the number of glucosemonomeric units can be at least 10, 50, 100, 500, 1000, 2000, 3000,4000, 5000, 6000, 7000, 8000, or 9000 (or any integer between 10 and9000), for example.

Poly alpha-1,3-1,6-glucan herein can be produced, for example, using aglucosyltransferase enzyme comprising an amino acid sequence that is atleast 90% identical to SEQ ID NO:2, SEQ ID NO:4, SEQ ID NO:6, SEQ IDNO:8, or SEQ ID NO:10. Alternatively, the glucosyltransferase enzyme cancomprise an amino acid sequence that is at least 91%, 92%, 93%, 94%,95%, 96%, 97%, 98%, or 99% identical to, or 100% identical to, SEQ IDNO:2, SEQ ID NO:4, SEQ ID NO:6, SEQ ID NO:8, or SEQ ID NO:10. Productionof poly alpha-1,3-1,6-glucan of the disclosed invention can beaccomplished with a gtf reaction as disclosed herein, for example.

Poly alpha-1,3-1,6-glucan herein can be provided in the form of a powderwhen dry, or a paste, colloid or other dispersion when wet, for example.A composition comprising poly alpha-1,3-1,6-glucan in certainembodiments is one in which the constituent poly alpha-1,3-1,6-glucanbehaves as a thickening agent. It is believed that polyalpha-1,3-1,6-glucan herein is suitable as a thickening agent, which isa substance that absorbs liquids such as water and swells upon suchabsorption. Swelling of poly alpha-1,3-1,6-glucan in a liquid can yielda slurry or colloid, for example.

A composition comprising poly alpha-1,3-1,6-glucan may be in the form ofa personal care product, pharmaceutical product, food product, householdproduct, or industrial product, such as any of those products disclosedbelow for the application of ether derivatives of polyalpha-1,3-1,6-glucan. The amount of poly alpha-1,3-1,6-glucan in thecomposition can be, for example, about 0.1-10 wt %, 0.1-5 wt %, 0.1-4 wt%, 0.1-3 wt %, 0.1-2 wt %, or 0.1-1 wt %, or an amount that provides thedesired degree of thickening to the composition.

Embodiments of the disclosed invention concern a composition comprisinga poly alpha-1,3-1,6-glucan ether compound, wherein:

(i) at least 30% of the glycosidic linkages of the polyalpha-1,3-1,6-glucan ether compound are alpha-1,3 linkages,

(ii) at least 30% of the glycosidic linkages of the polyalpha-1,3-1,6-glucan ether compound are alpha-1,6 linkages,

(iii) the poly alpha-1,3-1,6-glucan ether compound has a weight averagedegree of polymerization (DP_(w)) of at least 1000;

(iv) the alpha-1,3 linkages and alpha-1,6 linkages of the polyalpha-1,3-1,6-glucan ether compound do not consecutively alternate witheach other, and

(v) the poly alpha-1,3-1,6-glucan ether compound has a degree ofsubstitution (DoS) with an organic group of about 0.05 to about 3.0.

Significantly, a poly alpha-1,3-1,6-glucan ether compound disclosedherein has enhanced viscosity modification qualities such as the abilityto viscosify an aqueous composition at low concentration. Also, a polyalpha-1,3-1,6-glucan ether compound herein can have a relatively low DoSand still be an effective viscosity modifier.

At least 30% of the glycosidic linkages of a poly alpha-1,3-1,6-glucanether compound disclosed herein are alpha-1,3 linkages, and at least 30%of the glycosidic linkages of the poly alpha-1,3-1,6-glucan ethercompound are alpha-1,6 linkages. Alternatively, the percentage ofalpha-1,3 linkages in a poly alpha-1,3-1,6-glucan ether compound hereincan be at least 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, 40%, 41%,42%, 43%, 44%, 45%, 46%, 47%, 48%, 49%, 50%, 51%, 52%, 53%, 54%, 55%,56%, 57%, 58%, 59%, 60%, 61%, 62%, 63%, or 64%. Alternatively still, thepercentage of alpha-1,6 linkages in a poly alpha-1,3-1,6-glucan ethercompound herein can be at least 31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%,39%, 40%, 41%, 42%, 43%, 44%, 45%, 46%, 47%, 48%, 49%, 50%, 51%, 52%,53%, 54%, 55%, 56%, 57%, 58%, 59%, 60%, 61%, 62%, 63%, 64%, 65%, 66%,67%, 68%, or 69%.

A poly alpha-1,3-1,6-glucan ether compound of the invention can have anyone the aforementioned percentages of alpha-1,3 linkages and any one ofthe aforementioned percentages of alpha-1,6 linkages, just so long thatthe total of the percentages is not greater than 100%. For example, thepoly alpha-1,3-1,6-glucan ether compound can have (i) any one of 30%,31%, 32%, 33%, 34%, 35%, 36%, 37%, 38%, 39%, or 40% (30%-40%) alpha-1,3linkages and (ii) any one of 60%, 61%, 62%, 63%, 64%, 65%, 66%, 67%,68%, or 69% (60%-69%) alpha-1,6 linkages, just so long that the total ofthe percentages is not greater than 100%. Non-limiting examples includepoly alpha-1,3-1,6-glucan ether compounds with 31% alpha-1,3 linkagesand 67% alpha-1,6 linkages. Other examples of alpha-1,3 and alpha-1,6linkage profiles of certain poly alpha-1,3-1,6-glucan ether compoundsherein are provided in Table 2, which discloses linkage profiles ofisolated poly alpha-1,3-1,6-glucan that can be used to prepare thedisclosed ethers. In certain embodiments, at least 60% of the glycosidiclinkages of the poly alpha-1,3-1,6-glucan ether compound are alpha-1,6linkages.

A poly alpha-1,3-1,6-glucan ether compound of the invention can have,for example, less than 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, or 1% ofglycosidic linkages other than alpha-1,3 and alpha-1,6. In anotherembodiment, a poly alpha-1,3-1,6-glucan ether compound only hasalpha-1,3 and alpha-1,6 linkages.

The backbone of a poly alpha-1,3-1,6-glucan ether compound disclosedherein can be linear/unbranched. Alternatively, there can be branches inthe poly alpha-1,3-1,6-glucan ether compound. A polyalpha-1,3-1,6-glucan ether compound in certain embodiments can thus haveno branch points or less than about 30%, 29%, 28%, 27%, 26%, 25%, 24%,23%, 22%, 21%, 20%, 19%, 18%, 17%, 16%, 15%, 14%, 13%, 12%, 11%, 10%,9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, or 1% branch points as a percent of theglycosidic linkages in the polymer.

The alpha-1,3 linkages and alpha-1,6 linkages of a polyalpha-1,3-1,6-glucan ether compound disclosed herein do notconsecutively alternate with each other. For the following discussion,consider that . . . G-1,3-G-1,6-G-1,3-G-1,6-G-1,3-G- . . . (where Grepresents etherized glucose) represents a stretch of six glucosemonomeric units linked by consecutively alternating alpha-1,3 linkagesand alpha-1,6 linkages. Poly alpha-1,3-1,6-glucan ether compounds incertain embodiments herein less than 2, 3, 4, 5, 6, 7, 8, 9, 10, or moreglucose monomeric units that are linked consecutively with alternatingalpha-1,3 and alpha-1,6 linkages.

The molecular weight of a poly alpha-1,3-1,6-glucan ether compounddisclosed herein can be measured as DP_(w) (weight average degree ofpolymerization) or DP_(n) (number average degree of polymerization).Alternatively, molecular weight can be measured in Daltons orgrams/mole. It may also be useful to refer to the number-averagemolecular weight (M_(n)) or weight-average molecular weight (M_(w)) ofthe poly alpha-1,3-1,6-glucan ether compound.

A poly alpha-1,3-1,6-glucan ether compound herein has a DP_(w) of atleast about 1000. For example, the DP_(w) of the polyalpha-1,3-1,6-glucan ether compound can be at least about 10000.Alternatively, the DP_(w) can be at least about 1000 to about 15000.Alternatively still, the DP_(w) can be at least about 1000, 2000, 3000,4000, 5000, 6000, 7000, 8000, 9000, 10000, 11000, 12000, 13000, 14000,or 15000 (or any integer between 1000 and 15000), for example.

A poly alpha-1,3-1,6-glucan ether compound herein can have an M_(w) ofat least about 50000, 100000, 200000, 300000, 400000, 500000, 600000,700000, 800000, 900000, 1000000, 1100000, 1200000, 1300000, 1400000,1500000, or 1600000 (or any integer between 50000 and 1600000), forexample. The M_(w) in certain embodiments is at least about 1000000.

A poly alpha-1,3-1,6-glucan ether compound herein can comprise at least6 glucose monomeric units (most of such units typically containether-linked organic groups), for example. Alternatively, the number ofglucose monomeric units can be at least 10, 50, 100, 500, 1000, 2000,3000, 4000, 5000, 6000, 7000, 8000, or 9000 (or any integer between 10and 9000), for example.

Poly alpha-1,3-1,6-glucan ether compounds of the invention have a DoSwith an organic group of about 0.05 to about 3.0. In certainembodiments, the DoS of a poly alpha-1,3-1,6-glucan ether compound canbe about 0.3 to 1.0. The DoS can alternatively be at least about 0.1,0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1, 1.2, 1.3, 1.4, 1.5,1.6, 1.7, 1.8, 1.9, 2.0, 2.1, 2.2, 2.3, 2.4, 2.5, 2.6, 2.7, 2.8, 2.9, or3.0.

The percentage of glucose monomeric units of a poly alpha-1,3-1,6-glucanether compound herein that are ether-linked to an organic group (i.e.,where one or more hydroxyl groups of a glucose monomeric unit have beenetherified with an organic group) can vary depending on the degree towhich a poly alpha-1,3-1,6-glucan is etherified with an organic group inan etherification reaction. This percentage can be at least 30%, 40%,50%, 60%, 70%, 80%, 90%, or 100% (or any integer value between 30% and100%), for example.

It would be understood that, depending on the glycosidic linkages withwhich a glucose monomeric unit of an ether compound is involved (e.g.,-1,6-G-1,3-), certain carbon atoms of the glucose monomeric unit mayindependently be linked to an OH group or be in ether linkage to anorganic group.

An organic group herein may be an alkyl group such as a methyl, ethyl,propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, or decyl group, forexample.

Alternatively, an organic group may be a substituted alkyl group inwhich there is a substitution on one or more carbons of the alkyl group.The substitution(s) may be one or more hydroxyl, aldehyde, ketone,and/or carboxyl groups. For example, a substituted alkyl group may be ahydroxy alkyl group, dihydroxy alkyl group, or carboxy alkyl group.

Examples of suitable hydroxy alkyl groups are hydroxymethyl (—CH₂OH),hydroxyethyl (e.g., —CH₂CH₂OH, —CH(OH)CH₃), hydroxypropyl (e.g.,—CH₂CH₂CH₂OH, —CH₂CH(OH)CH₃, —CH(OH)CH₂CH₃), hydroxybutyl andhydroxypentyl groups. Other examples include dihydroxy alkyl groups(diols) such as dihydroxymethyl, dihydroxyethyl (e.g., —CH(OH)CH₂OH),dihydroxypropyl (e.g., —CH₂CH(OH)CH₂OH, —CH(OH)CH(OH)CH₃),dihydroxybutyl and dihydroxypentyl groups.

Examples of suitable carboxy alkyl groups are carboxymethyl (—CH₂COOH),carboxyethyl (e.g., —CH₂CH₂COOH, —CH(COOH)CH₃), carboxypropyl (e.g.,—CH₂CH₂CH₂COOH, —CH₂CH(COOH)CH₃, —CH(COOH)CH₂CH₃), carboxybutyl andcarboxypentyl groups.

Alternatively still, one or more carbons of an alkyl group can have asubstitution(s) with another alkyl group. Examples of such substituentalkyl groups are methyl, ethyl and propyl groups. To illustrate, anorganic group can be —CH(CH₃)CH₂CH₃ or —CH₂CH(CH₃)CH₃, for example,which are both propyl groups having a methyl substitution.

As should be clear from the above examples of various substituted alkylgroups, a substitution (e.g., hydroxy or carboxy group) on an alkylgroup in certain embodiments may be bonded to the terminal carbon atomof the alkyl group, where the terminal carbon group is opposite theterminus that is in ether linkage to a glucose monomeric unit in a polyalpha-1,3-1,6-glucan ether compound. An example of this terminalsubstitution is the hydroxypropyl group —CH₂CH₂CH₂OH. Alternatively, asubstitution may be on an internal carbon atom of an alkyl group. Anexample on an internal substitution is the hydroxypropyl group—CH₂CH(OH)CH₃. An alkyl group can have one or more substitutions, whichmay be the same (e.g., two hydroxyl groups [dihydroxy]) or different(e.g., a hydroxyl group and a carboxyl group).

Poly alpha-1,3-1,6-glucan ether compounds in certain embodimentsdisclosed herein may contain one type of organic group. Examples of suchcompounds contain a carboxy alkyl group as the organic group(carboxyalkyl poly alpha-1,3-1,6-glucan, generically speaking). Aspecific non-limiting example of such a compound is carboxymethyl polyalpha-1,3-1,6-glucan.

Alternatively, poly alpha-1,3-1,6-glucan ether compounds disclosedherein can contain two or more different types of organic groups.Examples of such compounds contain (i) two different alkyl groups asorganic groups, (ii) an alkyl group and a hydroxy alkyl group as organicgroups (alkyl hydroxyalkyl poly alpha-1,3-1,6-glucan, genericallyspeaking), (iii) an alkyl group and a carboxy alkyl group as organicgroups (alkyl carboxyalkyl poly alpha-1,3-1,6-glucan, genericallyspeaking), (iv) a hydroxy alkyl group and a carboxy alkyl group asorganic groups (hydroxyalkyl carboxyalkyl poly alpha-1,3-1,6-glucan,generically speaking), (v) two different hydroxy alkyl groups as organicgroups, or (vi) two different carboxy alkyl groups as organic groups.Specific non-limiting examples of such compounds include ethylhydroxyethyl poly alpha-1,3-1,6-glucan, hydroxyalkyl methyl polyalpha-1,3-1,6-glucan, carboxymethyl hydroxyethyl polyalpha-1,3-1,6-glucan, and carboxymethyl hydroxypropyl polyalpha-1,3-1,6-glucan.

Poly alpha-1,3-1,6-glucan ether compounds may be derived from any polyalpha-1,3-1,6-glucan disclosed herein. For example, a polyalpha-1,3-1,6-glucan ether compound of the invention can be produced byether-derivatizing poly alpha-1,3-1,6-glucan using an etherificationreaction as disclosed herein.

In certain embodiments of the disclosed invention, the polyalpha-1,3-1,6-glucan from which a poly alpha-1,3-1,6-glucan ethercompound is derived is a product of a glucosyltransferase enzymecomprising an amino acid sequence that is at least 90% identical to SEQID NO:2, SEQ ID NO:4, SEQ ID NO:6, SEQ ID NO:8, or SEQ ID NO:10.Alternatively, the glucosyltransferase enzyme can comprise an amino acidsequence that is at least 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99%identical to, or 100% identical to, SEQ ID NO:2, SEQ ID NO:4, SEQ IDNO:6, SEQ ID NO:8, or SEQ ID NO:10.

In certain embodiments of the disclosed invention, a compositioncomprising a poly alpha-1,3-1,6-glucan ether compound can be ahydrocolloid or aqueous solution having a viscosity of at least about 10cPs. Alternatively, such a hydrocolloid or aqueous solution has aviscosity of at least about 100, 250, 500, 750, 1000, 1250, 1500, 1750,2000, 2250, 2500, 3000, 3500, or 4000 cPs (or any integer between 100and 4000 cPs), for example.

Viscosity can be measured with the hydrocolloid or aqueous solution atany temperature between about 3° C. to about 110° C. (or any integerbetween 3 and 110° C.). Alternatively, viscosity can be measured at atemperature between about 4° C. to 30° C., or about 20° C. to 25° C.Viscosity can be measured at atmospheric pressure (about 760 torr) orany other higher or lower pressure.

The viscosity of a hydrocolloid or aqueous solution disclosed herein canbe measured using a viscometer or rheometer, or using any other meansknown in the art. It would be understood by those skilled in the artthat a viscometer or rheometer can be used to measure the viscosity ofthose hydrocolloids and aqueous solutions of the invention that exhibitshear thinning behavior or shear thickening behavior (i.e., liquids withviscosities that vary with flow conditions). The viscosity of suchembodiments can be measured at a rotational shear rate of about 10 to1000 rpm (revolutions per minute) (or any integer between 10 and 1000rpm), for example. Alternatively, viscosity can be measured at arotational shear rate of about 10, 60, 150, 250, or 600 rpm.

The pH of a hydrocolloid or aqueous solution disclosed herein can bebetween about 2.0 to about 12.0. Alternatively, pH can be about 2.0,3.0, 4.0, 5.0, 6.0, 7.0, 8.0, 9.0, 10.0, 11.0, 12.0; between about 4.0and 8.0; or between about 5.0 and 8.0.

A poly alpha-1,3-1,6-glucan ether compound disclosed herein can bepresent in a hydrocolloid or aqueous solution at a weight percentage (wt%) of at least about 0.01%, 0.05%, 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%,0.7%, 0.8%, 0.9%, 1.0%, 1.2%, 1.4%, 1.6%, 1.8%, 2.0%, 2.5%, 3.0%, 3.5%,4.0%, 4.5%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%,18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, or 30%, forexample.

A hydrocolloid or aqueous solution herein can comprise other componentsin addition to a poly alpha-1,3-1,6-glucan ether compound. For example,the hydrocolloid or aqueous solution can comprise one or more salts suchas a sodium salt (e.g., NaCl, Na₂SO₄). Other non-limiting examples ofsalts include those having (i) an aluminum, ammonium, barium, calcium,chromium (II or III), copper (I or II), iron (II or III), hydrogen, lead(II), lithium, magnesium, manganese (II or III), mercury (I or II),potassium, silver, sodium strontium, tin (II or IV), or zinc cation, and(ii) an acetate, borate, bromate, bromide, carbonate, chlorate,chloride, chlorite, chromate, cyanamide, cyanide, dichromate, dihydrogenphosphate, ferricyanide, ferrocyanide, fluoride, hydrogen carbonate,hydrogen phosphate, hydrogen sulfate, hydrogen sulfide, hydrogensulfite, hydride, hydroxide, hypochlorite, iodate, iodide, nitrate,nitride, nitrite, oxalate, oxide, perchlorate, permanganate, peroxide,phosphate, phosphide, phosphite, silicate, stannate, stannite, sulfate,sulfide, sulfite, tartrate, or thiocyanate anion. Thus, any salt havinga cation from (i) above and an anion from (ii) above can be in ahydrocolloid or aqueous solution, for example. A salt can be present ina hydrocolloid or aqueous solution at a wt % of about 0.01% to about10.00% (or any hundredth increment between 0.01 and 10.00).

Those skilled in the art would understand that in certain embodiments ofthe invention, a poly alpha-1,3-1,6-glucan ether compound can be in ananionic form in the hydrocolloid or aqueous solution. Examples mayinclude those poly alpha-1,3-1,6-glucan ether compounds having anorganic group comprising an alkyl group substituted with a carboxylgroup. Carboxyl (COON) groups in a carboxyalkyl polyalpha-1,3-1,6-glucan ether compound can convert to carboxylate (COO⁻)groups in aqueous conditions. Such anionic groups can interact with saltcations such as any of those listed above in (i) (e.g., potassium,sodium, or lithium cation). Thus, a poly alpha-1,3-1,6-glucan ethercompound can be a sodium carboxyalkyl poly alpha-1,3-1,6-glucan ether(e.g., sodium carboxymethyl poly alpha-1,3-1,6-glucan), potassiumcarboxyalkyl poly alpha-1,3-1,6-glucan ether (e.g., potassiumcarboxymethyl poly alpha-1,3-1,6-glucan), or lithium carboxyalkyl polyalpha-1,3-1,6-glucan ether (e.g., lithium carboxymethyl polyalpha-1,3-1,6-glucan), for example.

A poly alpha-1,3-1,6-glucan ether compound disclosed herein may becrosslinked using any means known in the art. Such crosslinks may beborate crosslinks, where the borate is from any boron-containingcompound (e.g., boric acid, diborates, tetraborates, pentaborates,polymeric compounds such as Polybor®, polymeric compounds of boric acid,alkali borates). Alternatively, crosslinks can be provided withpolyvalent metals such as titanium or zirconium. Titanium crosslinks maybe provided using titanium IV-containing compounds such as titaniumammonium lactate, titanium triethanolamine, titanium acetylacetonate,and polyhydroxy complexes of titanium. Zirconium crosslinks can beprovided using zirconium IV-containing compounds such as zirconiumlactate, zirconium carbonate, zirconium acetylacetonate, zirconiumtriethanolamine, zirconium diisopropylamine lactate and polyhydroxycomplexes of zirconium. Alternatively still, crosslinks can be providedwith any crosslinking agent described in U.S. Pat. Nos. 4,462,917;4,464,270; 4,477,360 and 4,799,550; which are all incorporated herein byreference. A crosslinking agent (e.g., borate) may be present in ahydrocolloid or aqueous solution at a concentration of about 0.2% to 20wt %, or about 0.1, 0.2, 0.3, 0.4, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10,15, or 20 wt %, for example.

It is believed that a poly alpha-1,3-1,6-glucan ether compound disclosedherein that is crosslinked typically has a higher viscosity in anaqueous solution compared to its non-crosslinked counterpart. Inaddition, it is believed that a crosslinked poly alpha-1,3-1,6-glucanether compound can have increased shear thickening behavior compared toits non-crosslinked counterpart.

Hydrocolloids and aqueous solutions in certain embodiments of theinvention are believed to have either shear thinning behavior or shearthickening behavior. Shear thinning behavior is observed as a decreasein viscosity of the hydrocolloid or aqueous solution as shear rateincreases, whereas shear thickening behavior is observed as an increasein viscosity of the hydrocolloid or aqueous solution as shear rateincreases. Modification of the shear thinning behavior or shearthickening behavior of an aqueous solution herein is due to theadmixture of a poly alpha-1,3-1,6-glucan ether to the aqueouscomposition. Thus, one or more poly alpha-1,3-1,6-glucan ether compoundsof the invention can be added to an aqueous liquid, solution, or mixtureto modify its rheological profile (i.e., the flow properties of theaqueous liquid, solution, or mixture are modified). Also, one or morepoly alpha-1,3-1,6-glucan ether compounds of the invention can be addedto an aqueous liquid, solution, or mixture to modify its viscosity.

The rheological properties of hydrocolloids and aqueous solutions of theinvention can be observed by measuring viscosity over an increasingrotational shear rate (e.g., from about 10 rpm to about 250 rpm). Forexample, shear thinning behavior of a hydrocolloid or aqueous solutiondisclosed herein can be observed as a decrease in viscosity (cPs) by atleast about 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%,65%, 70%, 75%, 80%, 85%, 90%, or 95% (or any integer between 5% and 95%)as the rotational shear rate increases from about 10 rpm to 60 rpm, 10rpm to 150 rpm, 10 rpm to 250 rpm, 60 rpm to 150 rpm, 60 rpm to 250 rpm,or 150 rpm to 250 rpm. As another example, shear thickening behavior ofa hydrocolloid or aqueous solution disclosed herein can be observed asan increase in viscosity (cPs) by at least about 5%, 10%, 15%, 20%, 25%,30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%,100%, 125%, 150%, 175%, or 200% (or any integer between 5% and 200%) asthe rotational shear rate increases from about 10 rpm to 60 rpm, 10 rpmto 150 rpm, 10 rpm to 250 rpm, 60 rpm to 150 rpm, 60 rpm to 250 rpm, or150 rpm to 250 rpm.

A hydrocolloid or aqueous solution disclosed herein can be in the formof, and/or comprised in, a personal care product, pharmaceuticalproduct, food product, household product, or industrial product. Polyalpha-1,3-1,6-glucan ether compounds disclosed herein can be used asthickening agents in each of these products. Such a thickening agent maybe used in conjunction with one or more other types of thickening agentsif desired, such as those disclosed in U.S. Pat. No. 8,541,041, thedisclosure of which is incorporated herein by reference in its entirety.

Personal care products herein are not particularly limited and include,for example, skin care compositions, cosmetic compositions, antifungalcompositions, and antibacterial compositions. Personal care productsherein may be in the form of, for example, lotions, creams, pastes,balms, ointments, pomades, gels, liquids, combinations of these and thelike. The personal care products disclosed herein can include at leastone active ingredient. An active ingredient is generally recognized asan ingredient that causes the intended pharmacological effect.

In certain embodiments, a skin care product can be applied to skin foraddressing skin damage related to a lack of moisture. A skin careproduct may also be used to address the visual appearance of skin (e.g.,reduce the appearance of flaky, cracked, and/or red skin) and/or thetactile feel of the skin (e.g., reduce roughness and/or dryness of theskin while improved the softness and subtleness of the skin). A skincare product typically may include at least one active ingredient forthe treatment or prevention of skin ailments, providing a cosmeticeffect, or for providing a moisturizing benefit to skin, such as zincoxide, petrolatum, white petrolatum, mineral oil, cod liver oil,lanolin, dimethicone, hard fat, vitamin A, allantoin, calamine, kaolin,glycerin, or colloidal oatmeal, and combinations of these. A skin careproduct may include one or more natural moisturizing factors such asceramides, hyaluronic acid, glycerin, squalane, amino acids,cholesterol, fatty acids, triglycerides, phospholipids,glycosphingolipids, urea, linoleic acid, glycosaminoglycans,mucopolysaccharide, sodium lactate, or sodium pyrrolidone carboxylate,for example. Other ingredients that may be included in a skin careproduct include, without limitation, glycerides, apricot kernel oil,canola oil, squalane, squalene, coconut oil, corn oil, jojoba oil,jojoba wax, lecithin, olive oil, safflower oil, sesame oil, shea butter,soybean oil, sweet almond oil, sunflower oil, tea tree oil, shea butter,palm oil, cholesterol, cholesterol esters, wax esters, fatty acids, andorange oil.

A personal care product herein can also be in the form of makeup orother product including, but not limited to, a lipstick, mascara, rouge,foundation, blush, eyeliner, lip liner, lip gloss, other cosmetics,sunscreen, sun block, nail polish, mousse, hair spray, styling gel, nailconditioner, bath gel, shower gel, body wash, face wash, shampoo, hairconditioner (leave-in or rinse-out), cream rinse, hair dye, haircoloring product, hair shine product, hair serum, hair anti-frizzproduct, hair split-end repair product, lip balm, skin conditioner, coldcream, moisturizer, body spray, soap, body scrub, exfoliant, astringent,scruffing lotion, depilatory, permanent waving solution, antidandruffformulation, antiperspirant composition, deodorant, shaving product,pre-shaving product, after-shaving product, cleanser, skin gel, rinse,toothpaste, or mouthwash, for example.

A pharmaceutical product herein can be in the form of an emulsion,liquid, elixir, gel, suspension, solution, cream, or ointment, forexample. Also, a pharmaceutical product herein can be in the form of anyof the personal care products disclosed herein. A pharmaceutical productcan further comprise one or more pharmaceutically acceptable carriers,diluents, and/or pharmaceutically acceptable salts. A polyalpha-1,3-1,6-glucan ether compound disclosed herein can also be used incapsules, encapsulants, tablet coatings, and as an excipients formedicaments and drugs.

Non-limiting examples of food products herein include vegetable, meat,and soy patties; reformed seafood; reformed cheese sticks; cream soups;gravies and sauces; salad dressing; mayonnaise; onion rings; jams,jellies, and syrups; pie filling; potato products such as French friesand extruded fries; batters for fried foods, pancakes/waffles and cakes;pet foods; beverages; frozen desserts; ice cream; cultured dairyproducts such as cottage cheese, yogurt, cheeses, and sour creams; cakeicing and glazes; whipped topping; leavened and unleavened baked goods;and the like.

Poly alpha-1,3-1,6-glucan ether compounds, hydrocolloids and aqueouscompositions disclosed herein can be used to provide one or more of thefollowing physical properties to a food product (or any personal careproduct, pharmaceutical product, or industrial product): thickening,freeze/thaw stability, lubricity, moisture retention and release, filmformation, texture, consistency, shape retention, emulsification,binding, suspension, and gelation, for example. Polyalpha-1,3-1,6-glucan ether compounds disclosed herein can typically beused in a food product at a level of about 0.01 to about 5 wt %, forexample.

A poly alpha-1,3-1,6-glucan ether compound disclosed herein can becomprised in a foodstuff or any other ingestible material (e.g., enteralpharmaceutical preparation) in an amount that provides the desireddegree of thickening. For example, the concentration or amount of a polyalpha-1,3-1,6-glucan ether compound in a product, on a weight basis, canbe about 0.1-3 wt %, 0.1-4 wt %, 0.1-5 wt %, or 0.1-10 wt %.

A household and/or industrial product herein can be in the form ofdrywall tape-joint compounds; mortars; grouts; cement plasters; sprayplasters; cement stucco; adhesives; pastes; wall/ceiling texturizers;binders and processing aids for tape casting, extrusion forming, andinjection molding and ceramics; spray adherents andsuspending/dispersing aids for pesticides, herbicides, and fertilizers;fabric softeners; laundry detergents; hard surface cleaners; airfresheners; polymer emulsions; gels such as water-based gels; surfactantsolutions; paints such as water-based paints; protective coatings;adhesives; sealants and caulks; inks such as water-based ink;metal-working fluids; emulsion-based metal cleaning fluids used inelectroplating, phosphatizing, galvanizing and/or general metal cleaningoperations; hydraulic fluids (e.g., those used for fracking in downholeoperations); and aqueous mineral slurries, for example.

The disclosed invention also concerns a method for increasing theviscosity of an aqueous composition. This method comprises contactingone or more poly alpha-1,3-1,6-glucan ether compounds with the aqueouscomposition, wherein:

(i) at least 30% of the glycosidic linkages of the polyalpha-1,3-1,6-glucan ether compound are alpha-1,3 linkages,

(ii) at least 30% of the glycosidic linkages of the polyalpha-1,3-1,6-glucan ether compound are alpha-1,6 linkages,

(iii) the poly alpha-1,3-1,6-glucan ether compound has a weight averagedegree of polymerization (DP_(w)) of at least 1000; and

(iv) the alpha-1,3 linkages and alpha-1,6 linkages of the polyalpha-1,3-1,6-glucan ether compound do not consecutively alternate witheach other.

The contacting step in this method results in increasing the viscosityof the aqueous composition. Any hydrocolloid and aqueous solutiondisclosed herein can be produced using this method.

An aqueous composition herein can be water (e.g., de-ionized water), anaqueous solution, or a hydrocolloid, for example. The viscosity of anaqueous composition before the contacting step, measured at about 20-25°C., can be about 0-10000 cPs (or any integer between 0-10000 cPs). Sincethe aqueous composition can be a hydrocolloid or the like in certainembodiments, it should be apparent that the method can be used toincrease the viscosity of aqueous compositions that are already viscous.

Contacting a poly alpha-1,3-1,6-glucan ether compound(s) disclosedherein with an aqueous composition increases the viscosity of theaqueous composition. The increase in viscosity can be an increase of atleast about 1%, 10%, 100%, 1000%, 100000%, or 1000000% (or any integerbetween 1% and 1000000%), for example, compared to the viscosity of theaqueous composition before the mixing or dissolving step. It should beapparent that very large percent increases in viscosity can be obtainedwith the disclosed method when the aqueous composition has little to noviscosity before the contacting step.

The contacting step in a method for increasing the viscosity of anaqueous composition can be performed by mixing or dissolving any polyalpha-1,3-1,6-glucan ether compound(s) disclosed herein in the aqueouscomposition by any means known in the art. For example, mixing ordissolving can be performed manually or with a machine (e.g., industrialmixer or blender, orbital shaker, stir plate, homogenizer, sonicator,bead mill). Mixing or dissolving can comprise a homogenization step incertain embodiments. Homogenization (as well as any other type ofmixing) can be performed for about 5 to 60, 5 to 30, 10 to 60, 10 to 30,5 to 15, or 10 to 15 seconds (or any integer between 5 and 60 seconds),or longer periods of time as necessary to mix a polyalpha-1,3-1,6-glucan ether compound with the aqueous composition. Ahomogenizer can be used at about 5000 to 30000 rpm, 10000 to 30000 rpm,15000 to 30000 rpm, 15000 to 25000 rpm, or 20000 rpm (or any integerbetween 5000 and 30000 rpm). Hydrocolloids and aqueous solutionsdisclosed herein prepared using a homogenization step can be termed ashomogenized hydrocolloids and aqueous solutions.

After a poly alpha-1,3-1,6-glucan ether compound is mixed with ordissolved into the aqueous composition, the resulting aqueouscomposition may be filtered, or may not be filtered. For example, anaqueous composition prepared with a homogenization step may or may notbe filtered.

The disclosed invention also concerns a method for producing a polyalpha-1,3-1,6-glucan ether compound. This method comprises: contactingpoly alpha-1,3-1,6-glucan in a reaction under alkaline conditions withat least one etherification agent comprising an organic group, whereinthe organic group is etherified to the poly alpha-1,3-1,6-glucan therebyproducing a poly alpha-1,3-1,6-glucan ether compound. Further regardingthis method:

(i) at least 30% of the glycosidic linkages of the polyalpha-1,3-1,6-glucan are alpha-1,3 linkages,

(ii) at least 30% of the glycosidic linkages of the polyalpha-1,3-1,6-glucan are alpha-1,6 linkages,

(iii) the poly alpha-1,3-1,6-glucan has a weight average degree ofpolymerization (DP_(w)) of at least 1000,

(iv) the alpha-1,3 linkages and alpha-1,6 linkages of the polyalpha-1,3-1,6-glucan do not consecutively alternate with each other, and

(v) the poly alpha-1,3-1,6-glucan ether compound has a degree ofsubstitution (DoS) with the organic group of about 0.05 to about 3.0.

A poly alpha-1,3-1,6-glucan ether compound produced by this method canoptionally be isolated.

Poly alpha-1,3-1,6-glucan is contacted in a reaction under alkalineconditions with at least one etherification agent comprising an organicgroup. This step can be performed, for example, by first preparingalkaline conditions by contacting poly alpha-1,3-1,6-glucan with asolvent and one or more alkali hydroxides to provide a mixture (e.g.,slurry) or solution. The alkaline conditions of the etherificationreaction can thus comprise an alkali hydroxide solution. The pH of thealkaline conditions can be at least about 11.0, 11.2, 11.4, 11.6, 11.8,12.0, 12.2, 12.4, 12.6, 12.8, or 13.0.

Various alkali hydroxides can be used, such as sodium hydroxide,potassium hydroxide, calcium hydroxide, lithium hydroxide, and/ortetraethylammonium hydroxide. The concentration of alkali hydroxide in apreparation with poly alpha-1,3-1,6-glucan and a solvent can be fromabout 1-70 wt %, 5-50 wt %, 5-10 wt %, 10-50 wt %, 10-40 wt %, or 10-30wt % (or any integer between 1 and 70 wt %). Alternatively, theconcentration of alkali hydroxide such as sodium hydroxide can be atleast about 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17,18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, or 30 wt %. An alkalihydroxide used to prepare alkaline conditions may be in a completelyaqueous solution or an aqueous solution comprising one or morewater-soluble organic solvents such as ethanol or isopropanol.Alternatively, an alkali hydroxide can be added as a solid to providealkaline conditions.

Various organic solvents that can optionally be included or used as themain solvent when preparing the etherification reaction includealcohols, acetone, dioxane, isopropanol and toluene, for example; noneof these solvents dissolve poly alpha-1,3-1,6-glucan. Toluene orisopropanol can be used in certain embodiments. An organic solvent canbe added before or after addition of alkali hydroxide. The concentrationof an organic solvent (e.g., isopropanol or toluene) in a preparationcomprising poly alpha-1,3-1,6-glucan and an alkali hydroxide can be atleast about 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80,85, or 90 wt % (or any integer between 10 and 90 wt %).

Alternatively, solvents that can dissolve poly alpha-1,3-1,6-glucan canbe used when preparing the etherification reaction. These solventsinclude, but are not limited to, lithium chloride(LiCl)/N,N-dimethyl-acetamide (DMAc), SO₂/diethylamine (DEA)/dimethylsulfoxide (DMSO), LiCl/1,3-dimethyl-2-imidazolidinone (DMI),N,N-dimethylformamide (DMF)/N₂O₄, DMSO/tetrabutyl-ammonium fluoridetrihydrate (TBAF), N-methylmorpholine-N-oxide (NMMO), Ni(tren)(OH)₂[tren¼tris(2-aminoethyl)amine] aqueous solutions and melts ofLiClO₄.3H₂O, NaOH/urea aqueous solutions, aqueous sodium hydroxide,aqueous potassium hydroxide, formic acid, and ionic liquids.

Poly alpha-1,3-1,6-glucan can be contacted with a solvent and one ormore alkali hydroxides by mixing. Such mixing can be performed during orafter adding these components with each other. Mixing can be performedby manual mixing, mixing using an overhead mixer, using a magnetic stirbar, or shaking, for example. In certain embodiments, polyalpha-1,3-1,6-glucan can first be mixed in water or an aqueous solutionbefore it is mixed with a solvent and/or alkali hydroxide.

After contacting poly alpha-1,3-1,6-glucan, solvent, and one or morealkali hydroxides with each other, the resulting composition canoptionally be maintained at ambient temperature for up to 14 days. Theterm “ambient temperature” as used herein refers to a temperaturebetween about 15-30° C. or 20-25° C. (or any integer between 15 and 30°C.). Alternatively, the composition can be heated with or without refluxat a temperature from about 30° C. to about 150° C. (or any integerbetween 30 and 150° C.) for up to about 48 hours. The composition incertain embodiments can be heated at about 55° C. for about 30 minutesor about 60 minutes. Thus, a composition obtained from mixing a polyalpha-1,3-1,6-glucan, solvent, and one or more alkali hydroxides witheach other can be heated at about 50, 51, 52, 53, 54, 55, 56, 57, 58,59, or 60° C. for about 30-90 minutes.

After contacting poly alpha-1,3-1,6-glucan, solvent, and one or morealkali hydroxides with each other, the resulting composition canoptionally be filtered (with or without applying a temperature treatmentstep). Such filtration can be performed using a funnel, centrifuge,press filter, or any other method and/or equipment known in the art thatallows removal of liquids from solids. Though filtration would removemuch of the alkali hydroxide, the filtered poly alpha-1,3-1,6-glucanwould remain alkaline (i.e., mercerized poly alpha-1,3-1,6-glucan),thereby providing alkaline conditions.

An etherification agent comprising an organic group is contacted withpoly alpha-1,3-1,6-glucan in a reaction under alkaline conditions in amethod herein of producing poly alpha-1,3-1,6-glucan ether compounds.For example, an etherification agent can be added to a compositionprepared by contacting poly alpha-1,3-1,6-glucan, solvent, and one ormore alkali hydroxides with each other as described above.Alternatively, an etherification agent can be included when preparingthe alkaline conditions (e.g., an etherification agent can be mixed withpoly alpha-1,3-1,6-glucan and solvent before mixing with alkalihydroxide).

An etherification agent herein refers to an agent that can be used toetherify one or more hydroxyl groups of glucose monomeric units of polyalpha-1,3-1,6-glucan with an organic group as disclosed herein. Examplesof such organic groups include alkyl groups, hydroxy alkyl groups, andcarboxy alkyl groups. One or more etherification agents may be used inthe reaction.

Etherification agents suitable for preparing an alkyl polyalpha-1,3-1,6-glucan ether compound include, for example, dialkylsulfates, dialkyl carbonates, alkyl halides (e.g., alkyl chloride),iodoalkanes, alkyl triflates (alkyl trifluoromethanesulfonates) andalkyl fluorosulfonates. Thus, examples of etherification agents forproducing methyl poly alpha-1,3-1,6-glucan ethers include dimethylsulfate, dimethyl carbonate, methyl chloride, iodomethane, methyltriflate and methyl fluorosulfonate. Examples of etherification agentsfor producing ethyl poly alpha-1,3-1,6-glucan ethers include diethylsulfate, diethyl carbonate, ethyl chloride, iodoethane, ethyl triflateand ethyl fluorosulfonate. Examples of etherification agents forproducing propyl poly alpha-1,3-1,6-glucan ethers include dipropylsulfate, dipropyl carbonate, propyl chloride, iodopropane, propyltriflate and propyl fluorosulfonate. Examples of etherification agentsfor producing butyl poly alpha-1,3-1,6-glucan ethers include dibutylsulfate, dibutyl carbonate, butyl chloride, iodobutane and butyltriflate.

Etherification agents suitable for preparing a hydroxyalkyl polyalpha-1,3-1,6-glucan ether compound include, for example, alkyleneoxides such as ethylene oxide, propylene oxide (e.g., 1,2-propyleneoxide), butylene oxide (e.g., 1,2-butylene oxide; 2,3-butylene oxide;1,4-butylene oxide), or combinations thereof. As examples, propyleneoxide can be used as an etherification agent for preparing hydroxypropylpoly alpha-1,3-1,6-glucan, and ethylene oxide can be used as anetherification agent for preparing hydroxyethyl polyalpha-1,3-1,6-glucan. Alternatively, hydroxyalkyl halides (e.g.,hydroxyalkyl chloride) can be used as etherification agents forpreparing hydroxyalkyl poly alpha-1,3-1,6-glucan. Examples ofhydroxyalkyl halides include hydroxyethyl halide, hydroxypropyl halide(e.g., 2-hydroxypropyl chloride, 3-hydroxypropyl chloride) andhydroxybutyl halide. Alternatively, alkylene chlorohydrins can be usedas etherification agents for preparing hydroxyalkyl polyalpha-1,3-1,6-glucan. Alkylene chlorohydrins that can be used include,but are not limited to, ethylene chlorohydrin, propylene chlorohydrin,butylene chlorohydrin, or combinations of these.

Etherification agents suitable for preparing a dihydroxyalkyl polyalpha-1,3-1,6-glucan ether compound include dihydroxyalkyl halides(e.g., dihydroxyalkyl chloride) such as dihydroxyethyl halide,dihydroxypropyl halide (e.g., 2,3-dihydroxypropyl chloride [i.e.,3-chloro-1,2-propanediol]), or dihydroxybutyl halide, for example.2,3-dihydroxypropyl chloride can be used to prepare dihydroxypropyl polyalpha-1,3-1,6-glucan, for example.

Etherification agents suitable for preparing a carboxyalkyl polyalpha-1,3-1,6-glucan ether compound may include haloalkylates (e.g.,chloroalkylate). Examples of haloalkylates include haloacetate (e.g.,chloroacetate), 3-halopropionate (e.g., 3-chloropropionate) and4-halobutyrate (e.g., 4-chlorobutyrate). For example, chloroacetate(monochloroacetate) (e.g., sodium chloroacetate) can be used as anetherification agent to prepare carboxymethyl poly alpha-1,3-1,6-glucan.

When producing a poly alpha-1,3-1,6-glucan ether compound with two ormore different organic groups, two or more different etherificationagents would be used, accordingly. For example, both an alkylene oxideand an alkyl chloride could be used as etherification agents to producean alkyl hydroxyalkyl poly alpha-1,3-1,6-glucan ether. Any of theetherification agents disclosed herein may therefore be combined toproduce poly alpha-1,3-1,6-glucan ether compounds with two or moredifferent organic groups. Such two or more etherification agents may beused in the reaction at the same time, or may be used sequentially inthe reaction. When used sequentially, any of the temperature-treatment(e.g., heating) steps disclosed below may optionally be used betweeneach addition. One may choose sequential introduction of etherificationagents in order to control the desired DoS of each organic group. Ingeneral, a particular etherification agent would be used first if theorganic group it forms in the ether product is desired at a higher DoScompared to the DoS of another organic group to be added.

The amount of etherification agent to be contacted with polyalpha-1,3-1,6-glucan in a reaction under alkaline conditions can bedetermined based on the DoS required in the poly alpha-1,3-1,6-glucanether compound being produced. The amount of ether substitution groupson each glucose monomeric unit in poly alpha-1,3-1,6-glucan ethercompounds produced herein can be determined using nuclear magneticresonance (NMR) spectroscopy. The molar substitution (MS) value for polyalpha-1,3-1,6-glucan has no upper limit. In general, an etherificationagent can be used in a quantity of at least about 0.05 mole per mole ofpoly alpha-1,3-1,6-glucan. There is no upper limit to the quantity ofetherification agent that can be used.

Reactions for producing poly alpha-1,3-1,6-glucan ether compounds hereincan optionally be carried out in a pressure vessel such as a Parrreactor, an autoclave, a shaker tube or any other pressure vessel wellknown in the art.

A reaction herein can optionally be heated following the step ofcontacting poly alpha-1,3-1,6-glucan with an etherification agent underalkaline conditions. The reaction temperatures and time of applying suchtemperatures can be varied within wide limits. For example, a reactioncan optionally be maintained at ambient temperature for up to 14 days.Alternatively, a reaction can be heated, with or without reflux, betweenabout 25° C. to about 200° C. (or any integer between 25 and 200° C.).Reaction time can be varied correspondingly: more time at a lowtemperature and less time at a high temperature.

In certain embodiments of producing carboxymethyl polyalpha-1,3-1,6-glucan, a reaction can be heated to about 55° C. for about3 hours. Thus, a reaction for preparing a carboxyalkyl polyalpha-1,3-1,6-glucan herein can be heated to about 50° C. to about 60°C. (or any integer between 50 and 60° C.) for about 2 hours to about 5hours, for example. Etherification agents such as a haloacetate (e.g.,monochloroacetate) may be used in these embodiments, for example.

Optionally, an etherification reaction herein can be maintained under aninert gas, with or without heating. As used herein, the term “inert gas”refers to a gas which does not undergo chemical reactions under a set ofgiven conditions, such as those disclosed for preparing a reactionherein.

All of the components of the reactions disclosed herein can be mixedtogether at the same time and brought to the desired reactiontemperature, whereupon the temperature is maintained with or withoutstirring until the desired poly alpha-1,3-1,6-glucan ether compound isformed. Alternatively, the mixed components can be left at ambienttemperature as described above.

Following etherification, the pH of a reaction can be neutralized.Neutralization of a reaction can be performed using one or more acids.The term “neutral pH” as used herein, refers to a pH that is neithersubstantially acidic or basic (e.g., a pH of about 6-8, or about 6.0,6.2, 6.4, 6.6, 6.8, 7.0, 7.2, 7.4, 7.6, 7.8, or 8.0). Various acids thatcan be used for this purpose include, but are not limited to, sulfuric,acetic (e.g., glacial acetic), hydrochloric, nitric, any mineral(inorganic) acid, any organic acid, or any combination of these acids.

A poly alpha-1,3-1,6-glucan ether compound produced in a reaction hereincan optionally be washed one or more times with a liquid that does notreadily dissolve the compound. For example, poly alpha-1,3-1,6-glucanether can typically be washed with alcohol, acetone, aromatics, or anycombination of these, depending on the solubility of the ether compoundtherein (where lack of solubility is desirable for washing). In general,a solvent comprising an organic solvent such as alcohol is preferred forwashing a poly alpha-1,3-1,6-glucan ether. A poly alpha-1,3-1,6-glucanether product can be washed one or more times with an aqueous solutioncontaining methanol or ethanol, for example. For example, 70-95 wt %ethanol can be used to wash the product. A poly alpha-1,3-1,6-glucanether product can be washed with a methanol:acetone (e.g., 60:40)solution in another embodiment.

A poly alpha-1,3-1,6-glucan ether produced in the disclosed reaction canbe isolated. This step can be performed before or after neutralizationand/or washing steps using a funnel, centrifuge, press filter, or anyother method or equipment known in the art that allows removal ofliquids from solids. An isolated poly alpha-1,3-1,6-glucan ether productcan be dried using any method known in the art, such as vacuum drying,air drying, or freeze drying.

Any of the above etherification reactions can be repeated using a polyalpha-1,3-1,6-glucan ether product as the starting material for furthermodification. This approach may be suitable for increasing the DoS of anorganic group, and/or adding one or more different organic groups to theether product.

The structure, molecular weight and DoS of a poly alpha-1,3-1,6-glucanether product can be confirmed using various physiochemical analysesknown in the art such as NMR spectroscopy and size exclusionchromatography (SEC).

Any of the embodiments of poly alpha-1,3-1,6-glucan described above canbe used in an etherification reaction herein. For example, the polyalpha-1,3-1,6-glucan used in an etherification reaction herein can be aproduct of a glucosyltransferase enzyme comprising an amino acidsequence that is at least 90% identical to SEQ ID NO:2, SEQ ID NO:4, SEQID NO:6, SEQ ID NO:8, or SEQ ID NO:10. Alternatively, theglucosyltransferase enzyme can comprise an amino acid sequence that isat least 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, or 99% identical to, or100% identical to, SEQ ID NO:2, SEQ ID NO:4, SEQ ID NO:6, SEQ ID NO:8,or SEQ ID NO:10.

Poly alpha-1,3-1,6-glucan used for preparing poly alpha-1,3-1,6-glucanether compounds herein can be enzymatically produced from sucrose usingone or more glucosyltransferase (gtf) enzymes. The polyalpha-1,3-1,6-glucan product of this enzymatic reaction can be purifiedbefore using it to prepare an ether. Alternatively, a polyalpha-1,3-1,6-glucan product of a gtf reaction can be used with littleor no processing for preparing poly alpha-1,3-1,6-glucan ethercompounds.

A poly alpha-1,3-1,6-glucan slurry can be used directly in any of theabove processes for producing a poly alpha-1,3-1,6-glucan ether compounddisclosed herein. As used herein, a “poly alpha-1,3-1,6-glucan slurry”refers to a mixture comprising the components of a gtf enzymaticreaction. A gtf enzymatic reaction can include, in addition to polyalpha-1,3-1,6-glucan itself, various components such as sucrose, one ormore gtf enzymes, glucose, fructose, leucrose, buffer, FermaSure®,soluble oligosaccharides, oligosaccharide primers, bacterial enzymeextract components, borates, sodium hydroxide, hydrochloric acid, celllysate, proteins and/or nucleic acids. Minimally, the components of agtf enzymatic reaction can include, in addition to polyalpha-1,3-1,6-glucan itself, sucrose, one or more gtf enzymes, glucoseand fructose, for example. In another example, the components of a gtfenzymatic reaction can include, in addition to poly alpha-1,3-1,6-glucanitself, sucrose, one or more gtf enzymes, glucose, fructose, leucroseand soluble oligosaccharides (and optionally bacterial enzyme extractcomponents). It should be apparent that poly alpha-1,3-1,6-glucan, whenin a slurry as disclosed herein, has not been purified or washed. Itshould also be apparent that a slurry represents a gtf enzymaticreaction that is complete or for which an observable amount of polyalpha-1,3-1,6-glucan has been produced, which forms a solid since it isinsoluble in the aqueous reaction milieu (pH of 5-7, for example). Apoly alpha-1,3-1,6-glucan slurry can be prepared by setting up a gtfreaction as disclosed herein.

Alternatively, a wet cake of poly alpha-1,3-1,6-glucan can be useddirectly in any of the above processes for producing a polyalpha-1,3-1,6-glucan ether compound disclosed herein. A “wet cake ofpoly alpha-1,3-1,6-glucan” as used herein refers to polyalpha-1,3-1,6-glucan that has been separated (e.g., filtered) from aslurry and washed with water or an aqueous solution. A wet cake can bewashed at least 1, 2, 3, 4, 5, or more times, for example. The polyalpha-1,3-1,6-glucan is not dried when preparing a wet cake. A wet cakeis termed as “wet” given the retention of water by the washed polyalpha-1,3-1,6-glucan.

A wet cake of poly alpha-1,3-1,6-glucan can be prepared using any deviceknown in the art for separating solids from liquids, such as a filter orcentrifuge. For example, poly alpha-1,3-1,6-glucan solids in a slurrycan be collected on a funnel using a mesh screen over filter paper.Filtered wet cake can be resuspended in water (e.g., deionized water)and filtered one or more times to remove soluble components of theslurry such as sucrose, fructose and leucrose. As another example forpreparing a wet cake, poly alpha-1,3-1,6-glucan solids from a slurry canbe collected as a pellet via centrifugation, resuspended in water (e.g.,deionized water), and re-pelleted and resuspended one or more additionaltimes.

Non-limiting examples of compositions and methods disclosed hereininclude:

-   1. A reaction solution comprising water, sucrose and a    glucosyltransferase enzyme that synthesizes poly    alpha-1,3-1,6-glucan, wherein the glucosyltransferase enzyme    comprises an amino acid sequence that is at least 90% identical to    SEQ ID NO:2, SEQ ID NO:4, SEQ ID NO:6, SEQ ID NO:8, or SEQ ID NO:10.-   2. The reaction solution of embodiment 1, wherein    -   (i) at least 30% of the glycosidic linkages of the glucan are        alpha-1,3 linkages,    -   (ii) at least 30% of the glycosidic linkages of the glucan are        alpha-1,6 linkages, and    -   (iii) the glucan has a weight average degree of polymerization        (DP_(w)) of at least 1000.-   3. The reaction solution of embodiment 1 or 2, wherein at least 60%    of the glycosidic linkages of the glucan are alpha-1,6 linkages.-   4. The reaction solution of embodiment 1, 2, or 3, wherein the    DP_(w) of the glucan is at least 10000.-   5. The reaction solution of embodiment 1, 2, 3 or 4, wherein the    glucosyltransferase enzyme comprises the amino acid sequence of SEQ    ID NO:2, SEQ ID NO:4, SEQ ID NO:6, SEQ ID NO:8, or SEQ ID NO:10.-   6. A method for producing poly alpha-1,3-1,6-glucan comprising:    -   a) contacting at least water, sucrose, and a glucosyltransferase        enzyme that synthesizes poly alpha-1,3-1,6-glucan, wherein the        glucosyltransferase enzyme comprises an amino acid sequence that        is at least 90% identical to SEQ ID NO:2, SEQ ID NO:4, SEQ ID        NO:6, SEQ ID NO:8, or SEQ ID NO:10;        -   whereby poly alpha-1,3-1,6-glucan is produced; and    -   b) optionally, isolating the poly alpha-1,3-1,6-glucan produced        in step (a).-   7. The method of embodiment 6, wherein    -   (i) at least 30% of the glycosidic linkages of the glucan are        alpha-1,3 linkages,    -   (ii) at least 30% of the glycosidic linkages of the glucan are        alpha-1,6 linkages, and    -   (iii) the glucan has a weight average degree of polymerization        (DP_(w)) of at least 1000.-   8. The method of embodiment 6 or 7, wherein at least 60% of the    glycosidic linkages of the glucan are alpha-1,6 linkages.-   9. The method of embodiment 6, 7, or 8, wherein the DP_(w) of the    glucan is at least 10000.

EXAMPLES

The disclosed invention is further defined in Examples 1-8 providedbelow. It should be understood that these Examples, while indicatingcertain preferred aspects of the invention, are given by way ofillustration only. From the above discussion and these Examples, oneskilled in the art can ascertain the essential characteristics of thisinvention, and without departing from the spirit and scope thereof, canmake various changes and modifications of the invention to adapt it tovarious uses and conditions.

Abbreviations

The meanings of some of the abbreviations used herein are as follows:“g” means gram(s), “h” means hour(s), “mL” means milliliter(s), “psi”means pound(s) per square inch, “wt %” means weight percentage, “μm”means micrometer(s), “° C.” means degrees Celsius, “mg” meansmilligram(s), “mm” means millimeter(s), “μL” means microliter(s), “mmol”means millimole(s), “min” means minute(s), “mol %” means mole percent,“M” means molar, “mM” means millimolar, “N” means normal, “rpm” meansrevolutions per minute, “w/v” means weight for volume, “MPa” meansmegaPascal(s), “LB means Luria broth, “nm means nanometer(s), “OD” meansoptical density, “IPTG” means isopropyl-beta-D-thio-galactoside, “xg”means gravitational force, “SDS-PAGE” means sodium dodecyl sulfatepolyacrylamide electrophoresis, “DTT” means dithiothreitol, “BCA” meansbicinchoninic acid, “DMAc” means N,N′-dimethyl acetamide, “DMSO” meansdimethylsulfoxide, “NMR” means nuclear magnetic resonance, “SEC” meanssize exclusion chromatography, “DI water” means deionized water.

Materials

T10 dextran (D9260), IPTG, (cat#I6758), triphenyltetrazolium chloride,and BCA protein assay kit/reagents were obtained from the Sigma Co. (St.Louis, Mo.). BELLCO spin flasks were from the Bellco Co. (Vineland,N.J.). LB medium was from Becton, Dickinson and Company (Franklin Lakes,N.J.). Suppressor 7153 antifoam was obtained from Cognis Corporation(Cincinnati, Ohio). All other chemicals were obtained from commonly usedsuppliers of such chemicals.

Seed Medium

The seed medium used to grow starter cultures for the fermenterscontained: yeast extract (AMBEREX 695, 5.0 grams per liter, g/L), K₂HPO₄(10.0 g/L), KH₂PO₄ (7.0 g/L), sodium citrate dihydrate (1.0 g/L),(NH₄)₂SO₄ (4.0 g/L), MgSO₄ heptahydrate (1.0 g/L) and ferric ammoniumcitrate (0.10 g/L). The pH of the medium was adjusted to 6.8 usingeither 5N NaOH or H₂SO₄ and the medium was sterilized in the flask.Post-sterilization additions included glucose (20 mL/L of a 50% w/wsolution) and ampicillin (4 mL/L of a 25 mg/mL stock solution).

Fermenter Medium

The growth medium used in the fermenter contained: KH₂PO₄ (3.50 g/L),FeSO₄ heptahydrate (0.05 g/L), MgSO₄ heptahydrate (2.0 g/L), sodiumcitrate dihydrate (1.90 g/L), yeast extract (AMBEREX 695, 5.0 g/L),Suppressor 7153 antifoam (0.25 mL/L), NaCl (1.0 g/L), CaCl₂ dihydrate(10 g/L), and NIT trace elements solution (10 mL/L). The NIT traceelements solution contained citric acid monohydrate (10 g/L), MnSO₄hydrate (2 g/L), NaCl (2 g/L), FeSO₄ heptahydrate (0.5 g/L), ZnSO₄heptahydrate (0.2 g/L), CuSO₄ pentahydrate (0.02 g/L) and NaMoO₄dihydrate (0.02 g/L). Post-sterilization additions included glucose(12.5 g/L of a 50% w/w solution) and ampicillin (4 mL/L of a 25 mg/mLstock solution).

General Methods Production of Recombinant Glucosyltransferase (Gtf)Enzymes in Fermentation

Production of a recombinant gtf enzyme in a fermenter was initiated bypreparing a pre-seed culture of an E. coli strain expressing the gtfenzyme. A 10-mL aliquot of seed medium was added into a 125-mLdisposable baffled flask and inoculated with a 1.0-mL aliquot of the E.coli strain in 20% glycerol. The culture was allowed to grow at 37° C.while shaking at 300 rpm for 3 hours.

A seed culture, which was used for starting growth for gtf fermentation,was prepared by charging a 2-L shake flask with 0.5 L of seed medium.1.0 mL of the pre-seed culture was aseptically transferred into 0.5-Lseed medium in the flask and cultivated at 37° C. and 300 rpm for 5hours. The seed culture was transferred at an optical density 550 nm(OD₅₅₀)>2 to a 14-L fermenter (Braun, Perth Amboy, N.J.) containing 8 Lof fermenter medium at 37° C.

The E. coli strain was allowed to grow in the fermenter medium. Glucose(50% w/w glucose solution containing 1% w/w MgSO₄.7H₂O) was fed to thisculture when its glucose concentration decreased to 0.5 g/L. The glucosefeed was started at 0.36 grams feed per minute (g feed/min) andincreased progressively each hour to 0.42, 0.49, 0.57, 0.66, 0.77, 0.90,1.04, 1.21, 1.41 1.63, 1.92, and 2.2 g feed/min, respectively. The feedrate remained constant afterwards. Glucose concentration in the mediumwas monitored using an YSI glucose analyzer (YSI, Yellow Springs, Ohio).When glucose concentration exceeded 0.1 g/L, the feed rate was decreasedor stopped temporarily. Induction of gtf enzyme expression, which wasperformed when cells reached an OD₅₅₀ of 70, was initiated by adding 9mL of 0.5 M IPTG. The dissolved oxygen (DO) concentration was controlledat 25% of air saturation. The DO was controlled first by impelleragitation rate (400 to 1200 rpm) and later by aeration rate (2 to 10standard liters per minute, slpm). Culture pH was controlled at 6.8using NH₄OH (14.5% w/v) and H₂SO₄ (20% w/v). Back pressure wasmaintained at 0.5 bars. At various intervals (20, 25 and 30 hours), 5 mLof Suppressor 7153 antifoam was added to the fermenter to suppressfoaming. Cells were harvested by centrifugation 8 hours post IPTGaddition and were stored at −80° C. as a cell paste.

The cell paste obtained from fermentation for each gtf enzyme wassuspended at 150 g/L in 50 mM potassium phosphate buffer, pH 7.2, toprepare a slurry. The slurry was homogenized at 12,000 psi (Rannie-typemachine, APV-1000 or APV 16.56) and the homogenate chilled to 4° C. Withmoderately vigorous stirring, 50 g of a floc solution (Sigma Aldrich no.409138, 5% in 50 mM sodium phosphate buffer, pH 7.0) was added per literof cell homogenate. Agitation was reduced to light stirring for 15minutes. The cell homogenate was then clarified by centrifugation at4500 rpm for 3 hours at 5-10° C. Supernatant, containing gtf enzyme, wasconcentrated (approximately 5×) with a 30 kiloDalton (kDa) cut-offmembrane to render a gtf extract.

Determination of Gtf Enzymatic Activity

Gtf enzyme activity was confirmed by measuring the production ofreducing sugars (fructose and glucose) in a gtf reaction solution. Areaction solution was prepared by adding a gtf extract (prepared asabove) to a mixture containing sucrose (50 g/L), potassium phosphatebuffer (pH 6.5, 50 mM), and dextran T10 (1 mg/mL); the gtf extract wasadded to 5% by volume. The reaction solution was then incubated at22-25° C. for 24-30 hours, after which it was centrifuged. Supernatant(0.01 mL) was added to a mixture containing 1 N NaOH and 0.1%triphenyltetrazolium chloride (Sigma-Aldrich). The mixture was incubatedfor five minutes after which its OD_(480nm) was determined using anULTROSPEC spectrophotometer (Pharmacia LKB, New York, N.Y.) to gauge thepresence of the reducing sugars fructose and glucose.

Determination of Glycosidic Linkages

Glycosidic linkages in glucan products synthesized by a gtf enzyme weredetermined by ¹³C NMR (nuclear magnetic resonance) or ¹H NMR.

For ¹³C NMR, dry glucan polymer (25-30 mg) was dissolved in 1 mL ofdeuterated DMSO containing 3% by weight of LiCl with stirring at 50° C.Using a glass pipet, 0.8 mL of the solution was transferred into a 5-mmNMR tube. A quantitative ¹³C NMR spectrum was acquired using a BrukerAvance 500-MHz NMR spectrometer (Billerica, Mass.) equipped with a CPDULcryoprobe at a spectral frequency of 125.76 MHz, using a spectral windowof 26041.7 Hz. An inverse-gated decoupling pulse sequence using waltzdecoupling was used with an acquisition time of 0.629 second, aninter-pulse delay of 5 seconds, and 6000 pulses. The time domain datawas transformed using an exponential multiplication of 2.0 Hz.

For ¹H NMR, approximately 20 mg of a glucan polymer sample was weighedinto a vial on an analytical balance. The vial was removed from thebalance and 0.8 mL of deuterated DMSO (DMSO-d6), containing 3% by weightof LiCl, was added to the vial. The mixture was stirred with a magneticstir bar and warmed to 90° C. until the glucan sample dissolved. Thesolution was allowed to cool to room temperature. While stirring at roomtemperature, 0.2 mL of a 20% by volume solution of trifluoroacetic acid(TFA) in DMSO-d6 was added to the polymer solution. The TFA was added inorder to move all hydroxyl proton signals out of the region of thespectrum where carbohydrate ring proton signals occur. A portion, 0.8mL, of the final solution was transferred, using a glass pipet, into a5-mm NMR tube. A quantitative ¹H NMR spectrum was acquired using an NMRspectrometer with a proton frequency of 500 MHz or greater. The spectrumwas acquired using a spectral window of 11.0 ppm and a transmitteroffset of 5.5 ppm. A 90° pulse was applied for 32 pulses with aninter-pulse delay of 10 seconds and an acquisition time of 1.5 seconds.The time domain data were transformed using an exponentialmultiplication of 0.15 Hz.

Determination of Weight Average Degree of Polymerization (DP_(w))

The DP_(w) of a glucan product synthesized by a gtf enzyme wasdetermined by SEC. Dry glucan polymer was dissolved in DMAc and 5% LiCl(0.5 mg/mL) with shaking overnight at 100° C. The SEC system used was anAlliance™ 2695 separation module from Waters Corporation (Milford,Mass.) coupled with three online detectors: a differential refractometer2410 from Waters, a multiangle light scattering photometer Heleos™ 8+from Wyatt Technologies (Santa Barbara, Calif.), and a differentialcapillary viscometer ViscoStar™ from Wyatt. The columns used for SECwere four styrene-divinyl benzene columns from Shodex (Japan) and twolinear KD-806M, KD-802 and KD-801 columns to improve resolution at thelow molecular weight region of a polymer distribution. The mobile phasewas DMAc with 0.11% LiCl. The chromatographic conditions used were 50°C. in the column and detector compartments, 40° C. in the sample andinjector compartment, a flow rate of 0.5 mL/min, and an injection volumeof 100 μL. The software packages used for data reduction were Empower™version 3 from Waters (calibration with broad glucan polymer standard)and Astra® version 6 from Wyatt (triple detection method with columncalibration).

Example 1 Production of Gtf Enzyme 4297 (SEQ ID NO:2)

This Example describes preparing an N-terminally truncated version of aStreptococcus oralis gtf enzyme identified in GENBANK under GI number7684297 (SEQ ID NO:2, encoded by SEQ ID NO:1; herein referred to as“4297”).

A nucleotide sequence encoding gtf 4297 was synthesized using codonsoptimized for protein expression in E. coli (DNA2.0, Inc., Menlo Park,Calif.). The nucleic acid product (SEQ ID NO:1), encoding gtf 4297 (SEQID NO:2), was subcloned into pJexpress404® (DNA2.0, Inc.) to generatethe plasmid construct identified as pMP70. This plasmid construct wasused to transform E. coli MG1655 (ATCC™ 47076) cells to generate thestrain identified as MG1655/pMP70.

Production of gtf 4297 by bacterial expression and determination of itsenzymatic activity were performed following the procedures disclosed inthe General Methods section. The linkage profile and DP_(w) of glucanproduced by 4297 are shown in Table 2 (see Example 6 below).

Example 2 Production of Gtf Enzyme 3298 (SEQ ID NO:4)

This Example describes preparing an N-terminally truncated version of aStreptococcus sp. C150 gtf enzyme identified in GENBANK under GI number322373298 (SEQ ID NO:4, encoded by SEQ ID NO:3; herein referred to as“3298”).

A nucleotide sequence encoding gtf 3298 was synthesized using codonsoptimized for protein expression in E. coli (DNA2.0, Inc.). The nucleicacid product (SEQ ID NO:3), encoding gtf 3298 (SEQ ID NO:4), wassubcloned into pJexpress404® to generate the plasmid constructidentified as pMP98. This plasmid construct was used to transform E.coli MG1655 (ATCC™ 47076) cells to generate the strain identified asMG1655/pMP98.

Production of gtf 3298 by bacterial expression and determination of itsenzymatic activity were performed following the procedures disclosed inthe General Methods section. The linkage profile and DP_(w) of glucanproduced by 3298 are shown in Table 2 (see Example 6 below).

Example 3 Production of Gtf Enzyme 0544 (SEQ ID NO:6)

This Example describes preparing an N-terminally truncated version of aStreptococcus mutans gtf enzyme identified in GENBANK under GI number290580544 (SEQ ID NO:6, encoded by SEQ ID NO:5; herein referred to as“0544”).

A nucleotide sequence encoding gtf 0544 was synthesized using codonsoptimized for protein expression in E. coli (DNA2.0, Inc.). The nucleicacid product (SEQ ID NO:5), encoding gtf 0544 (SEQ ID NO:6), wassubcloned into pJexpress404® to generate the plasmid constructidentified as pMP67. This plasmid construct was used to transform E.coli MG1655 (ATCC™ 47076) cells to generate the strain identified asMG1655/pMP67.

Production of gtf 0544 by bacterial expression and determination of itsenzymatic activity were performed following the procedures disclosed inthe General Methods section. The linkage profile and DP_(w) of glucanproduced by 0544 are shown in Table 2 (see Example 6 below).

Example 4 Production of Gtf Enzyme 5618 (SEQ ID NO:8)

This Example describes preparing an N-terminally truncated version of aStreptococcus sanguinis gtf enzyme identified in GENBANK under GI number328945618 (SEQ ID NO:8, encoded by SEQ ID NO:7; herein referred to as“5618”).

A nucleotide sequence encoding gtf 5618 was synthesized using codonsoptimized for protein expression in E. coli (DNA2.0, Inc.). The nucleicacid product (SEQ ID NO:7), encoding gtf 5618 (SEQ ID NO:8), wassubcloned into pJexpress404® to generate the plasmid constructidentified as pMP72. This plasmid construct was used to transform E.coli MG1655 (ATCC™ 47076) cells to generate the strain identified asMG1655/pMP72.

Production of gtf 5618 by bacterial expression and determination of itsenzymatic activity were performed following the procedures disclosed inthe General Methods section. The linkage profile and DP_(w) of glucanproduced by 5618 are shown in Table 2 (see Example 6 below).

Example 5 Production of Gtf Enzyme 2379 (SEQ ID NO:10)

This Example describes preparing an N-terminally truncated version of aStreptococcus salivarius gtf enzyme identified in GENBANK under GInumber 662379 (SEQ ID NO:10, encoded by SEQ ID NO:9; herein referred toas “2379”).

A nucleotide sequence encoding gtf 2379 was synthesized using codonsoptimized for protein expression in E. coli (DNA2.0, Inc.). The nucleicacid product (SEQ ID NO:9), encoding gtf 2379 (SEQ ID NO:10), wassubcloned into pJexpress404® to generate the plasmid constructidentified as pMP65. This plasmid construct was used to transform E.coli MG1655 (ATCC™ 47076) cells to generate the strain identified asMG1655/pMP65.

Production of gtf 2379 by bacterial expression and determination of itsenzymatic activity were performed following the procedures disclosed inthe General Methods section. The linkage profile and DP_(w) of glucanproduced by 2379 are shown in Table 2 (see Example 6 below).

Example 6 Production of Insoluble Glucan Polymer with Gtf Enzymes

This Example describes using the gtf enzymes prepared in the aboveExamples to synthesize glucan polymer.

Reactions were performed with each of the above gtf enzymes followingthe procedures disclosed in the General Methods section. Briefly, gtfreaction solutions were prepared comprising sucrose (50 g/L), potassiumphosphate buffer (pH 6.5, 50 mM) and a gtf enzyme (2.5% extract byvolume). After 24-30 hours at 22-25° C., insoluble glucan polymerproduct was harvested by centrifugation, washed three times with water,washed once with ethanol, and dried at 50° C. for 24-30 hours.

Following the procedures disclosed in the General Methods section, theglycosidic linkages in the insoluble glucan polymer product from eachreaction were determined by ¹³C NMR, and the DP_(w) for each product wasdetermined by SEC. The results of these analyses are shown in Table 2.

TABLE 2 Linkages and DP_(w) of Glucan Produced by Various Gtf EnzymesGlucan Alpha SEQ ID Linkages Gtf NO. % 1,3 % 1,6 DP_(w) 4297 2 31 6710540 3298 4 50 50 1235 0544 6 62 36 3815 5618 8 34 66 3810 2379 10 3763 1640

Thus, gtf enzymes capable of producing insoluble glucan polymer having aheterogeneous glycosidic linkage profile (alpha-1,3 and 1,6 linkages)and a DP_(w) of at least 1000 were identified. These enzymes can be usedto produce insoluble poly alpha-1,3-1,6-glucan suitable forderivatization to downstream products such as glucan ether, asdemonstrated below in Example 7.

Example 7 Preparation of Carboxymethyl Poly Alpha-1,3-1,6-Glucan

This Example describes producing the glucan ether derivative,carboxymethyl poly alpha-1,3-1,6-glucan.

Poly alpha-1,3-1,6-glucan was first prepared as in Example 6, but with afew modifications. Specifically, a glucan polymerization reactionsolution was prepared comprising sucrose (300 g), potassium phosphatebuffer (pH 5.5; 8.17 g), gtf enzyme 4297 extract (90 mL) in 3 Ldistilled water. After 24-30 hours at 22-25° C., insoluble glucanpolymer was harvested by centrifugation, filtered, washed three timeswith water, washed twice with ethanol, and dried at 50° C. for 24-30hours. About 12 g of poly alpha-1,3-1,6-glucan was obtained.

The DP_(w) and glycosidic linkages of the insoluble glucan polymer wasdetermined as described in the General Methods. The polymer had a DPw of10,540 and a linkage profile of 31% alpha-1,3 and 67% alpha-1,6. It hada weight-average molecular weight (M_(w)) of 1100000. This solid glucanwas used to prepare carboxymethyl poly alpha-1,3-1,6-glucan as follows.

1 g of the poly alpha-1,3-1,6-glucan was added to 20 mL of isopropanolin a 50-mL capacity round bottom flask fitted with a thermocouple fortemperature monitoring and a condenser connected to a recirculatingbath, and a magnetic stir bar. Sodium hydroxide (40 mL of a 15%solution) was added dropwise to the preparation, which was then heatedto 25° C. on a hotplate. The preparation was stirred for 1 hour beforethe temperature was increased to 55° C. Sodium monochloroacetate (0.3 g)was then added to provide a reaction, which was held at 55° C. for 3hours before being neutralized with glacial acetic acid. The solidmaterial was then collected by vacuum filtration and washed with ethanol(70%) four times, dried under vacuum at 20-25° C., and analyzed by NMRto determine degree of substitution (DoS) of the solid. The solid wasidentified as sodium carboxymethyl poly alpha-1,3-1,6-glucan with a DoSof 0.464 (sample 1D in Table 3).

Table 3 provides a list of DoS measurements for additional samples ofcarboxymethyl poly alpha-1,3-1,6-glucan prepared using processes similarto the above process, but with certain modifications as indicated in thetable. Each reaction listed in Table 3 used poly alpha-1,3-1,6-glucanwith an M_(w) of 1100000 as substrate. The results in Table 3 indicatethat by altering the reagent amounts and time of the etherificationreaction, product DoS can be altered.

TABLE 3 Samples of Sodium Carboxymethyl Poly Alpha-1,3-1,6-GlucanPrepared from Poly Alpha-1,3-1,6-Glucan Product Reaction SampleReagent^(a):Glucan NaOH:Glucan Time Designation Molar Ratio^(b) MolarRatio^(b) (hours) DoS 1A 1.66 1.68 3 0.827 1B 0.83 1.92 1.5 0.648 1C0.83 1.08 3 0.627 1D 0.41 1.08 3 0.464 ^(a)Reagent refers to sodiummonochloroacetate. ^(b)Molar ratios calculated as moles of reagent permoles of poly alpha-1,3-1,6-glucan (second column), or moles of NaOH permoles of poly alpha-1,3-1,6-glucan (third column).

Thus, the glucan ether derivative, carboxymethyl polyalpha-1,3-1,6-glucan, was prepared and isolated.

Example 8 Viscosity Modification Using Carboxymethyl PolyAlpha-1,3-1,6-Glucan

This Example describes the effect of carboxymethyl polyalpha-1,3-1,6-glucan on the viscosity of an aqueous composition.

Various sodium carboxymethyl poly alpha-1,3-1,6 glucan samples (1A-1D)were prepared as described in Example 72. To prepare 0.6 wt % solutionsof each of these samples, 0.102 g of sodium carboxymethyl polyalpha-1,3-1,6-glucan was added to DI water (17 g). Each preparation wasthen mixed using a bench top vortexer at 1000 rpm until the solid wascompletely dissolved.

To determine the viscosity of carboxymethyl poly alpha-1,3-1,6-glucan,each solution of the dissolved glucan ether samples was subjected tovarious shear rates using a Brookfield III+ viscometer equipped with arecirculating bath to control temperature (20° C.). The shear rate wasincreased using a gradient program which increased from 0.1-232.5 rpmand the shear rate was increased by 4.55 (1/s) every 20 seconds. Resultsof this experiment at 14.72 (1/s) are listed in Table 4.

TABLE 4 Viscosity of Carboxymethyl Poly Alpha-1,3-1,6-Glucan Solutionsat Various Shear Rates Sample Loading Viscosity Sample (wt %) (cPs) 1A0.6 106.35^(a) 1B 0.6 48.92^(a) 1C 0.6 633.83^(a) 1D 0.6 2008.45^(b)^(a)Viscosity at 14.72 rpm. ^(b)Viscosity at 17.04 rpm

The results summarized in Table 4 indicate that a low concentration (0.6wt %) of carboxymethyl poly alpha-1,3-1,6-glucan can increase theviscosity of DI water when dissolved therein. Also, the results in Table4 indicate that a relatively low DoS (e.g., as low as 0.464, refer tosample 1D in Tables 3 and 4) is sufficient for carboxymethyl polyalpha-1,3-1,6-glucan to be an effective viscosity modifier of an aqueouscomposition.

It is noteworthy that the viscosity levels obtained with carboxymethylpoly alpha-1,3-1,6-glucan are substantially higher than the viscositylevels observed using carboxymethyl dextran (refer to comparativeExample 10) and carboxymethyl poly alpha-1,3-glucan (refer tocomparative Example 12) (compare Table 4 with Tables 6 and 8). This wasdespite these other agents having DoS levels similar with those of theabove carboxymethyl poly alpha-1,3-1,6-glucan samples (compare Table 3with Tables 5 and 7) and using these other agents at the sameconcentration (0.6 wt %).

Example 9 Comparative Preparation of Carboxymethyl Dextran from SolidDextran

This Example describes producing carboxymethyl dextran for use inExample 10.

0.5 g of solid dextran (M_(w)=750000) was added to 10 mL of isopropanolin a 50-mL capacity round bottom flask fitted with a thermocouple fortemperature monitoring and a condenser connected to a recirculatingbath, and a magnetic stir bar. Sodium hydroxide (0.9 mL of a 15%solution) was added dropwise to the preparation, which was then heatedto 25° C. on a hotplate. The preparation was stirred for 1 hour beforethe temperature was increased to 55° C. Sodium monochloroacetate (0.15g) was then added to provide a reaction, which was held at 55° C. for 3hours before being neutralized with glacial acetic acid. The solidmaterial was then collected by vacuum filtration and washed with ethanol(70%) four times, dried under vacuum at 20-25° C., and analyzed by NMRto determine degree of substitution (DoS) of the solid. The solid wasidentified as sodium carboxymethyl dextran.

Additional sodium carboxymethyl dextran was prepared using dextran ofdifferent M_(w). The DoS values of carboxymethyl dextran samplesprepared in this example are provided in Table 5.

TABLE 5 Samples of Sodium Carboxymethyl Dextran Prepared from SolidDextran Product Reaction Sample Dextran Reagent^(a):Dextran NaOH:DextranTime Designation M_(w) Molar Ratio^(b) Molar Ratio^(b) (hours) DoS 2A750000 0.41 1.08 3 0.64 2B 1750000 0.41 0.41 3 0.49 ^(a)Reagent refersto sodium monochloroacetate. ^(b)Molar ratios calculated as moles ofreagent per moles of dextran (third column), or moles of NaOH per molesof dextran (fourth column).

These carboxymethyl dextran samples were tested for their viscositymodification effects in Example 10.

Example 10 Comparative Effect of Shear Rate on Viscosity ofCarboxymethyl Dextran

This Example describes the viscosity, and the effect of shear rate onviscosity, of solutions containing the carboxymethyl dextran samplesprepared in Example 9.

Various sodium carboxymethyl dextran samples (2A and 2B) were preparedas described in Example 9. To prepare 0.6 wt % solutions of each ofthese samples, 0.102 g of sodium carboxymethyl dextran was added to DIwater (17 g). Each preparation was then mixed using a bench top vortexerat 1000 rpm until the solid was completely dissolved.

To determine the viscosity of carboxymethyl dextran at various shearrates, each solution of the dissolved dextran ether samples wassubjected to various shear rates using a Brookfield III+ viscometerequipped with a recirculating bath to control temperature (20° C.). Theshear rate was increased using a gradient program which increased from0.1-232.5 rpm and the shear rate was increased by 4.55 (1/s) every 20seconds. The results of this experiment at 14.72 (1/s) are listed inTable 6.

TABLE 6 Viscosity of Carboxymethyl Dextran Solutions at Various ShearRates Sample Viscosity Viscosity Viscosity Viscosity Loading (cPs) @(cPs) @ (cPs) @ (cPs) @ Sample (wt %) 66.18 rpm 110.3 rpm 183.8 rpm 250rpm 2A 0.6 4.97 2.55 4.43 3.88 2B 0.6 6.86 5.68 5.28 5.26

The results summarized in Table 6 indicate that 0.6 wt % solutions ofcarboxymethyl dextran have viscosities of about 2.5-7 cPs. Theseviscosity levels are substantially lower than the viscosity levelsobserved using carboxymethyl poly alpha-1,3-1,6-glucan samples at thesame low concentration (0.6 wt %) in water. Specifically, Table 4indicates that carboxymethyl poly alpha-1,3-1,6-glucan solutions haveviscosities of about 48-2010 cPs. This difference in viscositymodification is further noteworthy with respect to carboxymethyl dextransample 2B, which likely has a higher molecular weight than the molecularweights of the carboxymethyl poly alpha-1,3-1,6-glucan samples. Despitehaving a higher molecular weight, carboxymethyl dextran sample 2Bexhibited a substantially lower viscosity-modifying effect thancarboxymethyl poly alpha-1,3-1,6-glucan.

Thus, it is believed that carboxymethyl poly alpha-1,3-1,6-glucan has agreater viscosity-modifying effect than carboxymethyl dextran.

Example 11 Comparative Preparation of Carboxymethyl PolyAlpha-1,3-Glucan

This Example describes producing carboxymethyl poly alpha-1,3-glucan foruse in Example 12.

Poly alpha-1,3-glucan was prepared using a gtfJ enzyme preparation asdescribed in U.S. Patent Appl. Publ. No. 2013/0244288, which isincorporated herein by reference in its entirety.

150 g of poly alpha-1,3-glucan (M_(w)=192000) was added to 3000 mL ofisopropanol in a 500-mL capacity round bottom flask fitted with athermocouple for temperature monitoring and a condenser connected to arecirculating bath, and a magnetic stir bar. Sodium hydroxide (600 mL ofa 15% solution) was added dropwise to the preparation, which was thenheated to 25° C. on a hotplate. The preparation was stirred for 1 hourbefore the temperature was increased to 55° C. Sodium monochloroacetatewas then added to provide a reaction, which was held at 55° C. for 3hours before being neutralized with 90% acetic acid. The solid materialwas then collected by vacuum filtration and washed with ethanol (70%)four times, dried under vacuum at 20-25° C., and analyzed by NMR todetermine degree of substitution (DoS) of the solid. The solid wasidentified as sodium carboxymethyl poly alpha-1,3-glucan.

Additional sodium carboxymethyl poly alpha-1,3-glucan was prepared usingprocesses similar to the above process, but with certain modificationsas indicated in the Table 7. Each reaction listed in Table 7 used polyalpha-1,3-glucan with an M_(w) of 192000 as substrate.

TABLE 7 Samples of Carboxymethyl Poly Alpha-1,3-Glucan Product ReactionSample Reagent^(a):Glucan NaOH:Glucan Time Designation Molar Ratio^(b)Molar Ratio^(b) (hours) DoS C1A 3.297 2.4 3 0.977 C1B 1.65 2.4 3 0.514^(a)Reagent refers to sodium monochloroacetate. ^(b)Molar ratioscalculated as moles of reagent per moles of poly alpha-1,3-glucan(second column), or moles of NaOH per moles of poly alpha-1,3-glucan(third column).

These carboxymethyl poly alpha-1,3-glucan samples were tested for theirviscosity modification effects in Example 12.

Example 12 Comparative Viscosity Modification Using Carboxymethyl PolyAlpha-1,3-Glucan

This Example describes the effect of carboxymethyl poly alpha-1,3-glucanon the viscosity of an aqueous composition.

Various sodium carboxymethyl poly alpha-1,3-glucan samples (C1A and C1B)were prepared as described in Example 11. To prepare 0.6 wt % solutionsof each of these samples, 0.102 g of sodium carboxymethyl polyalpha-1,3-glucan was added to DI water (17 g). Each preparation was thenmixed using a bench top vortexer at 1000 rpm until the solid wascompletely dissolved.

To determine the viscosity of carboxymethyl poly alpha-1,3-glucan atvarious shear rates, each solution of the dissolved glucan ether sampleswas subjected to various shear rates using a Brookfield III+ viscometerequipped with a recirculating bath to control temperature (20° C.). Theshear rate was increased using a gradient program which increased from0.1-232.5 rpm and the shear rate was increased by 4.55 (1/s) every 20seconds. Results of this experiment at 14.72 (1/s) are listed in Table8.

TABLE 8 Viscosity of Carboxymethyl Poly Alpha-1,3-Glucan SolutionsSample Viscosity Loading (cPs) @ Sample (wt %) 14.9 rpm C1A 0.6 6.38 C1B0.6 21.27

The results summarized in Table 8 indicate that 0.6 wt % solutions ofcarboxymethyl poly alpha-1,3-glucan have viscosities of about 6-22 cPs.These viscosity levels are lower than the viscosity levels observedusing carboxymethyl poly alpha-1,3-1,6-glucan samples at the same lowconcentration (0.6 wt %) in water. Specifically, Table 4 indicates thatcarboxymethyl poly alpha-1,3-1,6-glucan solutions have viscosities ofabout 48-2010 cPs.

Thus, it is believed that carboxymethyl poly alpha-1,3-1,6-glucan mayhave a greater viscosity-modifying effect than carboxymethyl polyalpha-1,3-glucan.

Example 13 Comparative Viscosity Modification Using CarboxymethylCellulose

This Example describes the effect of carboxymethyl cellulose (CMC) onthe viscosity of an aqueous composition.

CMC samples (C3A and C3B, Table 9) obtained from DuPont Nutrition &Health (Danisco) were dissolved in DI water to prepare 0.6 wt %solutions of each sample.

To determine the viscosity of CMC at various shear rates, each solutionof the dissolved CMC samples was subjected to various shear rates usinga Brookfield III+ viscometer equipped with a recirculating bath tocontrol temperature (20° C.). The shear rate was increased using agradient program which increased from 0.1-232.5 rpm and the shear ratewas increased by 4.55 (1/s) every 20 seconds. Results of this experimentat 14.72 (1/s) are listed in Table 9.

TABLE 9 Viscosity of CMC Solutions Molecular Sample Weight LoadingViscosity (cPs) Sample (Mw) DoS (wt %) @ 14.9 rpm C3A (BAK 130) ~1300000.66  0.6 235.03 C3B (BAK 550) ~550000 0.734 0.6 804.31

CMC (0.6 wt %) therefore can increase the viscosity of an aqueoussolution. However, it is believed that this ability to increaseviscosity is lower than the ability of carboxymethyl polyalpha-1,3-1,6-glucan to increase viscosity.

Thus, it is believed that carboxymethyl poly alpha-1,3-1,6-glucan mayhave a greater viscosity-modifying effect than CMC.

What is claimed is:
 1. A reaction solution comprising water, sucrose anda glucosyltransferase enzyme that synthesizes poly alpha-1,3-1,6-glucan,wherein said glucosyltransferase enzyme comprises an amino acid sequencethat is at least 90% identical to SEQ ID NO:2, SEQ ID NO:4, SEQ ID NO:6,SEQ ID NO:8, or SEQ ID NO:10.
 2. The reaction solution of claim 1,wherein (i) at least 30% of the glycosidic linkages of said glucan arealpha-1,3 linkages, (ii) at least 30% of the glycosidic linkages of saidglucan are alpha-1,6 linkages, and (iii) said glucan has a weightaverage degree of polymerization (DP_(w)) of at least
 1000. 3. Thereaction solution of claim 2, wherein at least 60% of the glycosidiclinkages of said glucan are alpha-1,6 linkages.
 4. The reaction solutionof claim 2, wherein the DP_(w) of said glucan is at least
 10000. 5. Thereaction solution of claim 1, wherein said glucosyltransferase enzymecomprises the amino acid sequence of SEQ ID NO:2, SEQ ID NO:4, SEQ IDNO:6, SEQ ID NO:8, or SEQ ID NO:10.
 6. A method for producing polyalpha-1,3-1,6-glucan comprising: a) contacting at least water, sucrose,and a glucosyltransferase enzyme that synthesizes polyalpha-1,3-1,6-glucan, wherein said glucosyltransferase enzyme comprisesan amino acid sequence that is at least 90% identical to SEQ ID NO:2,SEQ ID NO:4, SEQ ID NO:6, SEQ ID NO:8, or SEQ ID NO:10; whereby polyalpha-1,3-1,6-glucan is produced; and b) optionally, isolating the polyalpha-1,3-1,6-glucan produced in step (a).
 7. The method of claim 6,wherein (i) at least 30% of the glycosidic linkages of said glucan arealpha-1,3 linkages, (ii) at least 30% of the glycosidic linkages of saidglucan are alpha-1,6 linkages, and (iii) said glucan has a weightaverage degree of polymerization (DP_(w)) of at least
 1000. 8. Themethod of claim 7, wherein at least 60% of the glycosidic linkages ofsaid glucan are alpha-1,6 linkages.
 9. The method of claim 7, whereinthe DP_(w) of said glucan is at least 10000.